The Glock Gen4 back strap replacement kit includes two gen4 size backstraps and two beavertail backstraps, trigger housing pin, and pin install tool. Glock Gen4 models G17,22,31,34,35, and 37.
the kit came with 2 medium beavertail backstraps instead of a medium and a large. Not really an issue since I needed the medium one anyways. Wish it was easier to get a hold of these kits in Canada as my glock 22 actually did not come with beavertail backstraps.