Natural voice Speak Thru provide voice transmission along with security. SSBRS models will fit into 4″ to 6″ diameter hole. 7″ Stainless Steel face plates are secured form the safe side to avoid tampering from the exterior. For ballistic levels 1 thru 3 UL listed laminated polycarbonate offsets face plates, for ballistic level 4 thru 8 prime painted HI-Ballistic steel to provided protection level required. ANVS Models will fit a 5″ diameter hole and is 6″ in diameter cast stainless steel with offset 1/4″ stainless steel for ballistic levels 1 thru 3 and prime painted HI-Hard Steel for levels 4 thru 8 to provide full range of ballistic protection required.