This is a Ruger Mag Release, model 90598.
This magazine release is compatible with all 10/22 autoloading rifle models and the Charger pistol. The release features ergonomic" fully ambidextrous push pockets" single finger release and flush-fit styling. Easy installation with no modification. Made in the USA.
Features:
Easy Installation
Fits 10/22 and 22 Charger
Ambidextrous