Nikon® P-Series Mounting System.
Forward thinking! Keep both your rifle and your scope happy. Nikon®'s P-Series System gives you room to establish proper mounting height and fore-aft positioning. Better shooting technique and comfortable eye relief are within reach. Works with standard size scopes or reverses to bring ultra-compact scopes closer. 1" tube. Weighs 5 ozs. Fits flat top picatinny rails.