"FASTENER SIZE: 3/16 INCH; RETAINER SIZE: ONLY NOMINAL MANDRELS ARE USED FOR NOMINAL & OVERSIZE RETAINERS; CLASS OF FIT: CLASS III; LENGTH: UP TO 1/2 IN LONG RETAINERS. WHILE ALL FORCETEC SYSTEM COMPONENTS PERFORM A SPECIFIC FUNCTION, THE MANDREL IS THE MOST CRITICAL. IT MUST NOT ONLY RESIST FRACTURE BUT MUST MAINTAIN PRECISE SIZE & SHAPE DURING THE INSTALLION PROCESS. THE MANDREL, WHEN DRAWN THROUGH THE RETAINER & SLEEVE, EXPANDS TO YIELD THE RETAINER & THE PARENT MATERIAL CAUSING RESIDUAL COMPRESSIVE STRESSES."