VERITAS - Dual trunnion mortice & marking gauge.  Use standard Veritas hard steel wheels which resist grain following

• 185mm overall
• Hardened steel wheel cutters
• Aluminum housing with brass face and stainless-steel rods
• Internal O-ring keeps light but constant friction on each rod
• Wheels can be oriented with opposing bevels
• Set projections up to 145mm, thumbscrew locks settings
• One rod has cutting edge at extreme end of rod for transferring dimensions
• Cutters retract into brass face for storage or for using one cutter at a time
• Eccentric placement of rods ensures large reference face, helps gauge resist rolling on surface
• Optional shaft clamp is designed to fit onto gauge's guide rods; lets you lock relative position of cutters while still being able to freely adjust fence for offset - see HERE
• Machined to precise tolerances to prevent binding on rods, the 1/2" long collar is made from extruded aluminum with a turned brass thumbscrew that tightens onto marking gauge's steel guide rods without marring their surfaces
  
  

See aa accessory trunnion lock HERE.