This is the new Rhino spring for the Axe, Mini and Defender markers.
The rhino spring is the go to spring for the Luxe, Vanquish, Shockers, Insights and now for the Axe, Mini and Defender guns.
This is a shorter then stock spring that in our testing showed better feet per second groupings and a higher feet per second over the longer and stronger stock spring.
Use this with any bolt! This is a drop in spring. No settings adjustments needed!