Hole Diameter include30, 25, 22, 16, 12 five types.

Shrapnel-type actuating mechanism. Contact Self-cleaning  Function. High Contact Reliability.
  Reliable operation in both electronic and traditional control systems at the voltage of 660V.
  Reliability in warm and wet climate and severe environment, level of protection up to IP65.
  Button mechanical life greater than 3 million times, indicator continuous working life greater than 100 thousand hours.
    Various button heads and indicator lights, satisfying different control requirements.