I bought this to adjust a new watchband that used the tightest pins ever made to connect the band's links.  My usual approach of using a metal scribe and a tack hammer to knock out the pins didn't work, so the watchband just lay in a drawer gathering dust.  I saw this gadget on Amazon and decided that I wasn't going to let an expensive watchband go to waste, and the price was low enough to take a chance.  I'm glad I did.

The action is not exceptionally precise (it is plastic, after all) and I don't think it will take a lot of punishment, but it only has one job to do and it does that well *provided* you are careful in how you apply it to the watchband. I was able to push out the link pins with slow but firm pressure on the screw drive mechanism and managed to break only one of the drive pins in the process (the drive pin was not centered on the link pin, doh!). Good thing there are 4 extra drive pins supplied in the packaging.  They just screw/unscrew into the working end of the screw drive mechanism.

Once I got the hang of the device and the amount of pressure needed to push out the pins without breaking the drive pin, it very simply and reliably drove out the pins. The instructions are so-so but once examined it's obvious how the device works, so the instructions can be ignored.