Federal contractor profile
MAINSTEM LLC
UEI SXHHGF88NPK4CAGE 63EE4
Active
Overview
- Legal name
- MAINSTEM LLC
- Also known as
- BLACKLYNX SERVICES
- Registered location
- ROCKVILLE, MD, USA
- Primary NAICS
- 541330 — Engineering Services
- Latest award activity
- Dec 5, 2025
Read company summary
MAINSTEM LLC is associated with UEI SXHHGF88NPK4 and CAGE 63EE4 in public federal records. AcornBids currently links 3 prime awards totaling $500 in obligations to this entity. Its largest recorded federal customer by obligations is Department of Defense. Its recorded federal awards include work classified as Research and Development in the Physical, Engineering, and Life Sciences (except Nanotechnology and Biotechnology); Computer Systems Design Services. These categories describe the loaded award records, not a complete list of company capabilities. Its primary SAM.gov NAICS is 541330 (Engineering Services). Its public SAM.gov registration lists ROCKVILLE, MD, USA.
At a glance
Lifetime prime obligations$500
Prime awards3
Awards with future end dates1
Top-agency concentration
Not available
Why this customer concentration
Detailed agency totals are not available in this stored profile.
Largest positive coded-agency total ÷ all positive coded-agency totals × 100
Missing data is shown as unavailable.
Prime contract obligations across loaded award records. Obligations are not revenue or contract ceilings. Summary updated Sep 28, 2026. Refresh pending; these totals may be out of date.
Business information
Public SAM.gov registration details.
- Legal name
- MAINSTEM LLC
- Doing business as
- BLACKLYNX SERVICES
- UEI
- SXHHGF88NPK4
- CAGE
- 63EE4
- Registered address
- 51 MONROE ST STE, ROCKVILLE, MD, 20850, USA
- Registration status
- Active
- Primary NAICS
- 541330 — Engineering Services
- SAM activation
- Jun 25, 2026
- Initial registration
- Aug 6, 2010
- Entity start
- Jul 28, 2010
- SAM updated
- Jun 25, 2026
- Registration expires
- Jun 24, 2027
- Fiscal year end
- Sep 30
- Place of incorporation
- MD, USA
Federal award analysis
Net transaction obligations by federal fiscal period.
Transaction history is not available in the loaded data. Annual funding is not estimated from current award totals.
Recent federal awards
Prime contract awards. Select an award to review its history and source evidence.
| Award / description | Awarding agency | Obligations | Start date | End date |
|---|---|---|---|---|
| HQ085926FF036SCALABLE HOMELAND INNOVATIVE ENTERPRISE LAYERED DEFENSE (SHIELD) INITIAL ORDER. | Department of Defense | $500 | Dec 29, 2025 | Dec 28, 2035 |
| HQ085926DF358THE CONTRACTOR SHALL PROVIDE ALL NECESSARY MATERIALS, LABOR, EQUIPMENT AND FACILITIES INCIDENTAL TO THE PERFORMANCE OF THIS REQUIREMENT IN ACCORDANCE WITH THE TERMS OF THE ORDER. | Department of Defense | $151.0B | Dec 29, 2025 | Not available |
| 47QTCA21D004MFEDERAL SUPPLY SCHEDULE CONTRACT | General Services Administration | $500.0K | Jan 27, 2021 | Not available |
Upcoming positioning windows
Modeled recompete windows are estimates, not announced solicitations or guarantees.
Registration, certifications & contacts
| Registration evidence | Date |
|---|---|
| SAM updated | Jun 25, 2026 |
| Source loaded | Sep 19, 2026 |
| Initial registration | Aug 6, 2010 |
| Entity start | Jul 28, 2010 |
| Industry | Reported size status |
|---|---|
| 334111 — Electronic Computer Manufacturing | Not reported |
| 334112 — Computer Storage Device Manufacturing | Not reported |
| 334118 — Computer Terminal and Other Computer Peripheral Equipment Manufacturing | Not reported |
| 423430 — Computer and Computer Peripheral Equipment and Software Merchant Wholesalers | Not reported |
| 513210 — Software Publishers | Not reported |
| 518210 — Computing Infrastructure Providers, Data Processing, Web Hosting, and Related Services | Not reported |
| 541330 — Engineering Services | Not reported |
| 541511 — Custom Computer Programming Services | Not reported |
| 541512 — Computer Systems Design Services | Not reported |
| 541513 — Computer Facilities Management Services | Not reported |
| 541519 — Other Computer Related Services | Not reported |
| 541690 — Other Scientific and Technical Consulting Services | Not reported |
| Contact | Role | Published contact methods | Evidence | Source date |
|---|---|---|---|---|
| ANNIE BAULER | Government business | Contact method not published | SAM registration | Not available |
| ELLEN SAUNDERS | Alternate government business | Contact method not published | SAM registration | Not available |
| ANNIE BAULER | Electronic business | Contact method not published | SAM registration | Not available |
Registered industries
- 334111 — Electronic Computer Manufacturing
- 334112 — Computer Storage Device Manufacturing
- 334118 — Computer Terminal and Other Computer Peripheral Equipment Manufacturing
- 423430 — Computer and Computer Peripheral Equipment and Software Merchant Wholesalers
- 513210 — Software Publishers
- 518210 — Computing Infrastructure Providers, Data Processing, Web Hosting, and Related Services
- 541330 — Engineering Services
- 541511 — Custom Computer Programming Services
- 541512 — Computer Systems Design Services
- 541513 — Computer Facilities Management Services
- 541519 — Other Computer Related Services
- 541690 — Other Scientific and Technical Consulting Services
Registration classifications and published certificates do not by themselves establish eligibility for a particular solicitation. View SAM source
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About MAINSTEM LLC
What products and services appear in its federal awards?
Recorded award industries: 541715 — Research and Development in the Physical, Engineering, and Life Sciences (except Nanotechnology and Biotechnology); 541512 — Computer Systems Design Services.
Recorded products and services: AC13 — NATIONAL DEFENSE R&D SERVICES; DEPARTMENT OF DEFENSE - MILITARY; EXPERIMENTAL DEVELOPMENT; DA01 — Support services for activities involved with application development and support to include analysis, design, development, coding, testing, and release packaging, as well as support of off-the-shelf Business Applications..
Examples from recent award records:
- SCALABLE HOMELAND INNOVATIVE ENTERPRISE LAYERED DEFENSE (SHIELD) INITIAL ORDER.
- THE CONTRACTOR SHALL PROVIDE ALL NECESSARY MATERIALS, LABOR, EQUIPMENT AND FACILITIES INCIDENTAL TO THE PERFORMANCE OF THIS REQUIREMENT IN ACCORDANCE WITH THE TERMS OF THE ORDER.
These records describe federal award work, not every company capability. Review the award evidence.
Where is the company registered?
51 MONROE ST STE, ROCKVILLE, Maryland 20850, United States
Registered location from SAM.gov; award performance locations may differ.
What is its primary registered industry?
541330 — Engineering Services.
Primary SAM.gov NAICS classification.
Which federal agencies are represented in its awards?
Department of Defense; General Services Administration.
Data coverage and methodology
Sources: SAM.gov registration, USAspending awards and transactions, and linked supporting records. Prime contract obligations, IDV ceilings and assistance amounts are kept separate. Missing records are not zero activity. Company claims are labeled separately. Recompete signals are rule-based scores out of 100. Positioning windows are AcornBids estimates.
No official subaward rows are loaded, so Acorn does not claim known teaming relationships.
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