Tanker Op Rod in Excellent Condition. The piston measures .5255 or better, the tab measures .095 or better and it's has been newly parkerized. This op rod is precision built to fit the Citadel or the Criterion tanker barrels on the market today. These barrels are sold by ammogarand.com, Gunparts.com, DGRGuns.com and Fulton Armory to name a few. If your building a tanker, getting a hold of a precision op rod is a must. Remember this will only fit the Citadel or the Criterion barrel, no other! These are file photos and a very good representation of what you will receive.