Smaller more efficient reliable—three features of the new Air Tool MTB Mini pump. With the new inverted double-chamber design this pump moves more air than the unit it replaced even more efficiently. Best of all it’s now available with a frame mounting bracket to keep it out of your backpack or pocket & easily accessible on your bike. Inverted double chamber design is smaller yet increases the air handling capacity by 20% when compared to our previous design reducing pumping time by up to two minutes. Twist locking head reduces size & can be easily converted to fit Presta or Schrader valves. Machined outer barrel for extra grip while pumping. Aluminum inner & outer chamber for durable performance. Max pressure: 60 PSI (4.1bar) Volume-per-stroke: 55cc Water bottle boss frame mounting bracket included. Water bottle boss frame mounting bracket included.