title: 12 mm
text: # 12 mm
  
  12 mm or 12 mm gauge may refer to:
  
  ## Rail transport modelling
  
  * TT gauge, 1:120 scale with rails 12 mm apart, representing standard gauge
  * HOn3½ gauge, 1:87.1 scale with rails 12 mm apart, representing 3-foot-6-inch gauge
  * H0m, 1:87 scale with rails 12 mm apart, representing metre gauge
  * 00n3, 1:76 scale with rails 12 mm apart, representing 3-foot gauge
  * 5.5 mm scale, 1:55 scale with rails 12 mm apart, representing narrow gauge
  * On2 gauge, 1:48 scale with rails 12.7 mm apart, representing narrow gauge
  
  ## Firearms
  
  * 12 mm caliber
  