Hi Ben, The Echelon ships with three backstraps – each with an integrated armorers tool. These patent-pending backstraps are universal and can be installed in the small, medium, and large grip frames. The medium backstrap comes installed on the pistol.
Stay safe & have a great day!

The Echelon ships with three backstraps – each with an integrated armorers tool. These patent-pending backstraps are universal and can be installed in the small, medium, and large grip frames.

Hi Benjamin and welcome. Yes, the medium backstrap is on the pistol and a small and large are included: youtube.com/watch?v=mzI05s2ApLw -------- Cheers, stay safe and enjoy!