Review on International KTI83091 Hammer RETAINER SPRING by Eric Williamson

The description says "Works with any standard .401" shank bit, but it will not fit the Ingersol Rand Model 121 Air Hammer with a standard .401 shank bit . If you manage to twist the spring enough to stretch it, you can force it into the threaded part of the pneumatic hammer, but the U-shaped hole in the front of the spring is also too small, so it will snag and snap on the shaft it doesn't move freely.