Tektro R559 brake caliper
You'll probably never need this much reach on a typical track bike but just in case you're riding a MASH Work or Steamroller with big honkin' tires and/or full fenders, the R559 is a high quality extra long reach caliper with refillable cartridge-type brake pads.
This is also what you'll probably need if you've converted an old road frame designed for using 27" wheels to 700c.
• dual-pivot design w/ forged aluminum arms
• quick release
• recessed nut
• adjustable angle Shimano-type cartridge pads
• sold individually - front or rear
• reach: 55-73mm
• colors: black, silver
• weight: 179g