Sealevel was founded with a commitment to providing reliable, innovative I/O and computing solutions to enable connectivity and control. For over 35 years, we’ve imagined, designed and manufactured critical communications hardware and software, made in the USA.

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Reinventing Industrial I/O and Embedded Computing

Sealevel Systems, Inc. reinvented the industrial I/O and computing industry with the first RS-422/485 communication adapter for the IBM PC. Since 1986, Sealevel has continued to redefine design, engineering and manufacturing for industrial computers, Ethernet serial servers, USB serial, PCI Express and PCI bus cards, and IoT hardware and software. Today we offer over 350 core products, available in nearly every configuration imaginable. If you need something completely customized to meet your specifications, we have that, too. Our award-winning team of engineers is at your service.

Sealevel is committed to a first-in-industry lifetime warranty on I/O and long-term availability of all products, beyond the life of your mission.


From custom electronic hardware and manufacturing services to standard products, Sealevel builds and assembles at our US headquarters for OEMs and wide-ranging industry leaders. Your product is subject to the highest quality standards and superior test procedures under ISO 9001:2015, developed in partnership with our in-house engineers.

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Our on-site Manufacturing processes include a complete SMT production line, through hole assembly, board-level testing, assembly, inventory, and shipping – all supported by and subject to our Quality department.

Sealevel’s facility has over 20,000 square feet of ESD tiling that spans our Manufacturing and Engineering departments.

Sealevel’s Receiving team operates within our Quality department and relies on software and other programs to verify drawings and dimensions as well as maintain parts traceability for identification and tracking.

Our SMT production line includes an automated screen printer, three high-speed SMT pick-and-place machines, a 10-zone convection reflow oven and a five-camera automated optical inspection (AOI) system.

Sealevel’s through-hole assembly technicians are J-STD-001 and IPC-A-610 certified for industry-leading performance.

Full functional testing is completed on all Sealevel standard I/O and computing products. On-site testing includes use of our transmissive x-ray machine, vibration table and series of walk-in thermal chambers.

Assembly adheres to comprehensive procedures for assembly, labeling and modification.

Our designated Special Projects area allows for enhanced physical security as required. This space is fully configurable to meet product assembly specifications for optimal production.

Our Facility

Sealevel’s 52,000 square foot facility sits on a 17-acre site. Our headquarters in Liberty, SC houses our business offices, engineering team, and manufacturing facility.

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Our in-house Engineering department includes hardware, software, mechanical, layout, compliance and test engineering teams. Our hardware design engineers specialize in complex computing and I/O design, excelling in SWaP optimization and functional density application. We have an extensive library of design work that addresses thermal and other environmental challenges that often impact mission critical communications.

The Sealevel Sales team has extensive, direct knowledge of our critical communications products and customer applications. This team is co-located with our Applications Engineers in Tech Support and our Marketing team for seamless information transfer.

Sealevel’s Applications Engineers are accessible throughout every stage of the customer relationship to assist with product selection and deployment. They have first-hand experience with all Sealevel hardware and software solutions and can guide customers through documentation and installation.

Sealevel’s team of customer service professionals focuses on continual customer support throughout the relationship lifecycle. A “master planning” approach allows for optimal scheduling of staff, equipment and inventory while dedicated program managers guide custom hardware development efforts.

Sealevel’s Accounting team has a holistic view of Sealevel’s ecosystem, facilitated by use of the industry-leading software NetSuite. With real-time, authoritative reporting in place, all departments have a cohesive view of Sealevel operations.

Our Procurement team focuses on vendor recruitment and relationship management. To best navigate the supply chain, they practice ongoing vendor education and communication as well as proactive discussions with Engineering to better ensure component availability.

Bolstered by careful analysis of industry and customer applications, our Marketing team is strategically involved from product conceptualization to official launch. The team capitalizes on communication and collaboration with partners, customers and prospects to best support their success and offer sustained informational programs.

Our Standards

Meeting & Exceeding Requirements

In the words of our founder, bring it on. Our engineering team designs technology to perform in the most extreme environments – implementing strategies to combat cold, heat, shock, vibration, and more. From initial planning and component selection through exhaustive testing, we’re up for your challenge. We have experience designing for a variety of defense and industrial standards, including MIL-STD-810, MIL-STD-461, MIL-STD-1472, MIL-STD-901, MIL-STD-464, MIL-STD-167-1; UI, CSA, FCC, CE; NEMA, IP and ATEX; Class I, Division 1; Class I, Division 2.

Our Standards


As part of our industry-leading commitment to customers, Sealevel continually evaluates and revises security practices for our products – both hardware and software – to comply with evolving standards. From tamper-evident hardware options and detailed cybersecurity planning, our standard products are subject to the highest protocols, and we are experienced in meeting custom requests as well. The Sealevel team is actively working toward CMMC and NIST 800-171 compliance.

Our Standards

Made in the USA

Sealevel was founded in Pickens County, at the base of the Blue Ridge Mountains, in 1986. Our leadership remains committed to employing American labor and giving back to the country – and neighbors – that have given so much to us. Unlike competitors, Sealevel has never relocated manufacturing outside of the USA, maintaining our rigorous control and quality standards.

Our Standards

Long-Term Availability

We’ve come to realize that this means different things to different people. For our competitors, long-term is 5-10 years. For us, it means that we’ll build it as long as you need it. And if we can’t build an identical solution, we’ll provide a form-fit-function replacement.

Our Standards

Lifetime Warranty

Sealevel was the first I/O provider in the industry to offer a lifetime warranty. We design and build our products to last: today, tomorrow, and beyond.

Our Standards


As the needs of our customers evolve, so do we. We started with I/O for critical communications and then expanded to provide embedded computing hardware and software. Those early I/O products were ISA, and we’ve transitioned from there to PCI, PCIe, USB and Ethernet connectivity to the host computer. Most recently, we’ve introduced IoT hardware and software to our product line and look forward to the continued development of new products that leverage emerging technology rooted in the foundations of intentional design.

Our Standards


We’re willing to bet passion is not the first word that comes to mind when you think engineering and manufacturing. But it is for us. From guidance before you make your selection to support after you receive your purchase, continuing for the life of our relationship, we’re passionate people. Passionate about what we do, passionate about what you do.

Our Standards

To Infinity

Sealevel products have their start in Liberty, South Carolina. After that, not even the sky is the limit. Our solutions are found across industries – defense, public safety, energy, monitoring, automation – and around the world. And yes, even in space.

Our Mission

Sealevel Systems, Inc. is committed to engineering leading-edge communications solutions, manufacturing our products to the highest quality standards, growing a creative team of trailblazers, and sustaining a legacy of community investment.

Our Story

Sealevel Systems, Inc. had its start in the early 1980s when founder Tom O’Hanlan was working in the textile environment. He learned then that if you could engineer and build something to work in those dusty, hot conditions that were also subject to shock and vibration, it could work nearly anywhere. Around the same time, early VoIP applications were being developed and released.
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Our Story

Sealevel Systems, Inc. had its start in the early 1980s when founder Tom O’Hanlan was working in the textile environment. He learned then that if you could engineer and build something to work in those dusty, hot conditions that were also subject to shock and vibration, it could work nearly anywhere. Around the same time, early VoIP applications were being developed and released.
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Enthusiasts Apply Here

Innovative mindset, exceptional culture and fair compensation.

Core Leadership

Meet the managers that keep our team shipshape.