The Marauder Trigger Spacer is used when a Marauder trigger is installed on a Benjamin Discovery or a Crosman 2xxx air tube. Because the M-rod tube wall thickness is .095 and the Disco is only .065, the M-rod sear sticks into the Disco .030 too far. The Marauder Trigger Spacer brings the sear and hammer back into proper alignment.
Usually, an M-rod trigger will work fine in a Disco, but because the sear is engaged to twice the normal depth, it doesn't disengage as cleanly as it does in the M-rod. The sear can drag excessively, or it can jam. There have been cases where the sear was actually broken during the normal hammer rebound. The Marauder Trigger Spacer can eliminate those problems.
WARNING: The trigger spacer must never be used on the standard thick-walled (.093-.095 thick) Marauder air tube. It should only be used on the thinner-walled (.063-.065 thick) tubes of the Benjamin Discovery and the 22xx series of Crosman airguns.