The Bar Fly 4 MTB is an “over the stem” mount compatible with all sizes of cycling computers. The modular system mounts your computer, Camera or Light to your bike. This out-front mount is compatible with 31.8mm and 35.0mm handlebars. BF4 MTB holds your computer behind the bars, over the stem. This position is safest for flat bars that don’t have “drops” for out-front protection. Swap the computer head for the included GoPro base and add your camera or light with compatible GoPro adapter.BF4 MTB bike mount is constructed from an advanced injection moulded co-polymer that is strong and weatherproof. The MTB bike mount can accommodate three different accessories at a time: computer, light, or camera.BF4 MTB is compatible with all bicycle GPS computers from Garmin, Wahoo, Bryton, Cateye, Polar, Mio, Joule, and (optional) Lezyne. BF4 MTB mounts on the right side of the stem and may conflict with electronic shifting display. If using electronic shifting, try BF4 Stem Cap Mount. Hammerhead computers fit Garmin head. Newer Pioneer computers fit Wahoo head. The computer clears the top of the mount, so even large computers are compatible.Included in the box: BF4 MTB composite mount with hardware, 7 Computer heads: Garmin, Polar, Wahoo, Mio, Joule, Cateye, Bryton, GoPro Base, Universal Light Mount, shim for 31.8 handlebars. Some bike light companies include a GoPro adapter, others offer it as an option (optional Lezyne head available).