The super quality all steel bases are strong and reliable. The Thompson Center All Steel Maxima 2 Piece Scope Base uses torx screws that can be tightened 25% more than conventional hex screws. Maxima rings fit all Weaver Style bases and Maxima bases can be used with all Weaver Style rings. The Thompson Center All Steel Maxima Scope Base can be used for Thompson Center 22 and 17 caliber Semi-Autos. 2 Piece, Matte Blue.