It is 172mm long when closed and has a 98mm long pump stroke. The barrel and shaft are aluminum. One of the things we like about this pump is that Blackburn hired a suspension fork engineer to work on their pump line. The result is mini-pumps that use the shaft space as an air chamber, which makes the pump action more stable and delivers more air per stroke. The Blackburn AirStik 2Stage comes with a mount that fits under a bottle cage. The head is designed for Presta valves only. Maximum pressure possible with the pump is 160psi. While this may not be important to you, Blackburn has made the pump so it can be rebuilt rather than tossed if a part breaks.