THE NAILDRIVER HAS A 10 CLICK KNOB FOR COMPUTER GENRATED SIGHT TAPE COMPATIBILITY; IT IS PROVEN TO BE THE TOUGHEST, MOST RELIABLE TARGET SIGHT ON THE MARKET TO DATE. THIS PARTICULAR MODEL IS COMPLETELY HAND MACHINED AND MATCH MILLED TO PERFECTION WITH THE PATENTED TOXONICS LOCKING MECHANISM. DEPRESS THE LOCK KNOB FOR RAPID MOVEMENTS; A SINGLE TWIST OF THE KNOB LOCKS THE SIGHT BLOCK AND LEAD SCREW FOR TWICE THE LOCKING POWER AND REPEATABILITY AS OTHER SIGHTS ON THE MARKET.