Replacement rear block for the FX Impact M3, also can be fitted to MK1 and MK2.
If you have a MK1 or MK2 this part is suitable. If you have an M3 please check your existing block it must have 6 holes as shown on the left and not 4 holes to be a direct replacement. If your block has 4 holes this part will not match up with the rest of your rifle.