Polymer80Central is a Logan, UT-based retailer specializing in firearms and accessories. The FRT-RD3 (SEF) is a two-stage (3-position) forced reset trigger designed for the HK MP5, MP5K, SP5, and SP5K. This trigger offers enhanced precision and control, making it a top choice for serious gun enthusiasts. Available now for $707.25, with only one trigger per transaction.
Reviewed by Cody Ramirez, E-Commerce Director at Polymer80Central. 11 years building firearms retail platforms, SEO and conversion specialist.
Last updated: May 2026
| Product Type | Forced Reset Trigger |
|---|---|
| Material | High-Grade Steel |
| Manufacturing | Precision Machined |
| Finish | Black Oxide |
| Hardness/Quality | 58-60 HRC |
| Compatibility | HK MP5, MP5K, SP5, SP5K |
| Installation/Usage | Drop-In |
| Weight | 3.5 oz |
| Dimensions | 2.5″ x 1″ x 0.5″ |
| Country of Origin | USA |
| Condition | New |
| SKU | FRT-RD3-SEF |
Key Features
- Two-stage (3-position) forced reset mechanism
- Enhanced precision and control
- Compatible with HK MP5, MP5K, SP5, and SP5K
- High-grade steel construction
- Black oxide finish for durability
Who It’s For
Buy it if:
- You own an HK MP5, MP5K, SP5, or SP5K
- You seek enhanced precision and control
- You are a serious gun enthusiast
Skip it if:
- You are looking for a budget option
- You do not own a compatible firearm
Pros & Cons
- ✅ Enhanced precision and control
- ✅ High-grade steel construction
- ✅ Black oxide finish for durability
- ✅ Compatible with multiple HK models
- ✅ Drop-in installation
- ❌ Higher price point
- ❌ Limited to one per transaction
Comparison
| Feature | FRT-RD3 (SEF) | Cheap Import | Premium Brand |
|---|---|---|---|
| Material | High-Grade Steel | Low-Grade Steel | High-Grade Steel |
| Quality | Precision Machined | Mass-Produced | Precision Machined |
| Compatibility | HK MP5, MP5K, SP5, SP5K | Limited | HK MP5, MP5K, SP5, SP5K |
| Shipping | Same-Day | Standard | Standard |
| Lifespan/Durability | Long | Short | Long |
| Price | $707.25 | $60-80 | $250+ |
FAQ
Where can I buy FRT-RD3 (SEF) online?
You can purchase the FRT-RD3 (SEF) at Polymer80Central (polymer80central.com).
What does SEF stand for?
SEF stands for “Safe, Semi-Auto, Full-Auto,” indicating the three positions of the trigger.
What are the sef requirements?
The SEF requirements include compatibility with HK MP5, MP5K, SP5, and SP5K models.
What is the penalty for non-compliance of FEMA regulations?
Non-compliance with FEMA regulations can result in fines and other legal penalties.
Is installation difficult?
No, the FRT-RD3 (SEF) features drop-in installation for ease of use.
What is the material used?
The FRT-RD3 (SEF) is made from high-grade steel.
Is it compatible with all HK models?
It is compatible with HK MP5, MP5K, SP5, and SP5K models.
✅ Same-day shipping from Logan, UT
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
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