Key Switch. 

High security tubular keyswitches for 12 volt residential, commercial and vehicle alarm systems. Stainless steel shunt On/Off. 

 Keyswitch Shunt On/Off

• Tubular security key switch with two keys and washer and plastic keyswitch cover.
• One position.
• Shunt On/ Off.
• Four terminals. Two pole.
• Two switches one always ON, one always OFF.
• With the key OUT (1st position) terminals A&B are closed and C&D are open.  Put the key in and turn to (2nd position) terminals A&B become open and C&D close, they key cannot be removed in this second position.
  
• Key can be removed from OFF position only.  When in ON position key stays within   lock.
  
• Dimensions 39mm x 16mm.
  
• Rated 12vdc at 2amp
  

(I also have  momentary / spring return key switches and metal key switch covers, please see my other listings ).