Now that you've selected all the parts to go in - and on - your Polymer80 slide, it's time to pick up some tools, hit the workbench, and put it all together. You need to install the safety plunger, extractor, extractor plunger spring and bearing, striker (firing pin) assembly, slide back plate, and of course, the sights. Sounds like a lot to do? C'mon, we're talking Glock® parts. As this video shows, it's basically plug-n-play.