Even if you're not mechanically inclined, this tool is easy to use and well worth the few bucks it cost.  I paid almost $20 to have an $80 watch resized awhile back. True, had I bought the watch in a store, they would've done it for free, but the $80 watch I bought on Amazon goes for almost $130 in brick and mortars.

The unit doesn't come with instructions, but it's fairly simple to figure out. Each watch's pins move a bit differently, but that's easy to figure out as well.  Then, just remove links, one at a time until the watch fits. Simple as that.

The unit itself is plastic, the interchangeable pins (a variety of sizes) are metal and store in the base of the unit. Overall, everything seems well made.

Well worth the money you'll save resizing just one watch.