These were my first real strap locks, when I bought them some years ago and placed them on my Ibanez ICT-700, which is a really heavy guitar. I sold the guitar with them, so when I bought my Standart Telecaster, I didn't think twice to buy these again.
The funcionality is good. The main goal for a strap lock, is to keep yout guitar safe in your hands, and here the Dunlops succeed. The use is very simple. The removal of the strap is just a button's push away. If you use them for a longer time, the button will start to jam a bit, but it only affects the removal of the strap - it will take a half a second more.
If you want to set them on your guitar by yourself, you should make sure you have a narrow screwdriver at home, because the hole where the bolt "sits" is quite small also.