This is a replacement spring for the AGP Arms 10 Round Magazine for the Saiga-12. The service limit for the springs when used in the 10rd mags is determined by measuring the free length of the spring. You simply take the spring out of the mag and measure it at it’s longest points. We consider the service limit to be 21”. As long as you are over 21” the spring should have the force needed to work reliably. Anything under 21” should be replaced.

This spring will also fit the factory 5 and 8 round magaines.