Peterson Lifter Valley Riser Tubes

Petersons Lifter Valley Riser tubes are installed in the lifter drain back holes to prevent oil drain back through these holes while allowing the engine to breath through the holes. 70 micron filter screens are installed in the tube opening. Installation requires that the lifter drain back holes are tapped 1/4" NPT. They have 9/16" Hex Top 1/4" NPT Thread Bottom. Set of 8.