The Tri-Phone Pro uses three point Bak2Bak (bidirectional) hook and loop mounting system for a secure attachment to the top tube and stem. The touch-sensitive phone compartment is large enough to accommodate large cell phones for on-the-go use. A YKK Uretek zipper with double sliders securely closes the bag and keeps the elements out. Foam sides and truck tarp interior keep the phone safe, even if your bike takes a beating*