Why is it a safety cutter?
The main blade is permanently spring-retracted and only comes out while you hold the thumb slide, so it is never left exposed in your pocket or on the bench.
What is the aperture for?
It is a protected slot for cutting string, tape and banding without exposing the main blade at all, which is the safest way to cut those.
Can I replace the blade?
Yes, a plastic screw fitting lets you open the housing and swap the blade simply when it dulls.
Is it hard wearing?
Yes, it has a die-cast metal housing, so it stands up to site use.
How do I use the main blade?
Push the thumb slide to extend it, cut, then release, and the spring pulls the blade back automatically.
How is it different from Snip Off?
This is a general box cutter for string, tape and packaging. Snip Off is a dedicated tool for opening sealant and adhesive cartridges cleanly.