Protecting your fire alarm pull stations from vandalism, false alarms, and accidental activation is essential for any commercial building. Safety Technology International (STI) makes the two most popular pull station protective covers in the industry: the Stopper II and the Universal Stopper. But which one is right for your facility?
In this guide, we’ll break down the differences, compatibility, and best use cases for each so you can make the right choice.
What Is the STI Stopper II?
The STI Stopper II is the most widely installed pull station protective cover in the world. Made from tough, clear polycarbonate, it mounts directly over your existing pull station and deters false alarms while still allowing legitimate emergency access.
Key Features:
- Tamperproof polycarbonate construction — virtually unbreakable and UV-resistant
- Lift-to-access design — lift from the bottom to reach the pull handle, guard pivots on top hinge
- Optional built-in horn — sounds a local alarm when the cover is lifted, drawing attention to potential false alarm attempts
- Flush mount (STI-1100, STI-1200) or surface mount (STI-1130, STI-1230) configurations
- Custom labeling available — ADA-compliant options and bilingual labels
Popular Models:
- STI-1100 — Stopper II with horn, flush mount
- STI-1130 — Stopper II with horn and spacer, surface mount
- STI-1200 — Stopper II without horn, flush mount
- STI-1230 — Stopper II without horn, surface mount
What Is the STI Universal Stopper?
The STI Universal Stopper is designed to fit virtually any brand of single-action pull station. If you have a mix of Notifier, Edwards, Simplex, or Fire-Lite pull stations in your building, the Universal Stopper is your best bet for standardized protection.
Key Features:
- Open-spacer design — accommodates pull stations from all major manufacturers
- Dome cover and low-profile options — choose the right fit for your installation
- Available with or without horn
- Enclosed or open backbox configurations
- Red, clear, and custom color options
Popular Models:
- STI-13010FR — Universal Stopper with horn, flush mount, red
- STI-13210FR — Universal Stopper dome cover with spacer, red
- STI-14200NR — Universal Stopper low profile with spacer
Stopper II vs Universal Stopper: Side-by-Side Comparison
- Compatibility: Stopper II fits most standard pull stations; Universal Stopper fits virtually ALL brands
- Profile: Stopper II is slimmer; Universal Stopper has a larger dome to accommodate varied pull station sizes
- Best for single-brand buildings: Stopper II (cleaner look, lower profile)
- Best for mixed-brand buildings: Universal Stopper (one cover fits everything)
- Price: Stopper II is generally less expensive; Universal Stopper costs slightly more for the added versatility
- Volume discounts: Both available in contractor 6-packs (CP6 models) for bulk installations
When to Choose the Weather Stopper Instead
If your pull stations are located outdoors — at loading docks, parking garages, building entrances, or exterior stairwells — you need an STI Weather Stopper instead. Weather Stoppers provide the same false alarm deterrence as the Stopper II but add sealed, weatherproof protection against rain, snow, dust, and UV exposure.
Need Help Choosing?
Not sure which STI cover is right for your pull stations? Contact Life Safety Consultants — our team has been helping facility managers, fire alarm contractors, and building owners choose the right protective covers since 2002. We stock the full STI product line and ship fast.
Browse all STI products: STI (Safety Technology International) →
