Q: How do I work metal fastening on strap?

This is on a medical device to protect me One end of cotton strap is attached to middle of clasp that have little moveable toothy thing. You've see 'em.
I need to be capable of pull closing stages of strap through it so it cinchs and STAYS TIGHT
Make it simple please

Answers:

I'm having severe distress in my thigh.?

I could do this for you easier than to explain it! The strap most predictable has a place where on earth it goes PAST the toothy subdivision, goes around and next comes back to the toothy subdivision. When you have it right, you will be capable of pull it tighter but it won't jump looser without pressing down on the right spot to release. That process it doesn't work loose accidentally and get lost.
Really, walk back to where on earth they gave/sold you this and have an assistant or nurse or someone fix it for you and show you how it works. If that isn't possible, budge by a hardware store, (the old fashioned helpful that has culture to help you!) and ask one of the workers within.
Live well and do perfect!