Bison tube

A Bison Tube (and a dime, to show relative size)

A bison tube is a small, metal, water-tight cylindrical container that can be used for micro-caches. These containers are usually small enough to fit on a keychain, and were originally designed to hold pills. The name is derived from the company which manufactures most of these types of tubes, Bison Designs.

Available sizes include:

• 2 3/8 x 5/8 in (Small)
• 2 3/4 x 5/8 in (Large)
• 2 x 3/4 in (Scuba Tank or Micro-Cache Capsule)
• 3 x 1 in (Extra Large)

Sources

• Bison Designs (search for "Capsule" or "Scuba Tank")
• Groundspeak
• South Mountain Traders
• CacheboxStore.com