This is a German made unit form WW1. The double set trigger is pretty unusual with a large "V" type spring to power it.
The double set trigger lets you compress a spring with the rear trigger that you can release with a light pull on the front trigger. This gets the trigger poundage significantly down on Mauser actions and lets you shoot more accurate. The kick off piece, often missing on those units, is included. Screw spacing is 7.835.
Length of the magazine opening is 3 1/4. I tried to capture every angle. Everything is working fine and moves freely.
Overall excellent condition, no rust pits, see pictures. This unit needs experienced gunsmith fitting. Trigger guards like these were common on the original German Pre WW2 Mauser sporting rifles from Europe and some of the early German sniper rifles. The item "Trigger guard WW1 Mauser 98 double set trigger, vintage rifle, with kickoff" is in sale since Thursday, April 07, 2016. This item is in the category "Sporting Goods\Hunting\Gun Parts\Rifle". The seller is "dosenroller" and is located in Pipersville, Pennsylvania. This item can be shipped to United States.