The Wolf Tooth Low Profile Shock Rebound Knob was created to prevent catching of the rebound adjustment knob. If you have a Fox rear shock that is mounted under your top tube, removing your bottle from its cage can catch the rebound adjustment knob and change your rebound without you knowing. This can lead to a rear suspension that packs up or one that bounces around. The Wolf Tooth crew noticed this issue and decided it was time to fix it.  The following brands have one or more models that could have this issue: Trek, Specialized, Cannondale, Pivot, Turner, Ibis, Yeti, Scott, Intense, Salsa.  There are bikes from other brands that have this issue as well.  If your water bottle is near the rebound knob, there is a very good chance your rebound setting is different than what you originally set. Wolf Tooth Low Profile Shock Rebound Knob Compatibility Fox FLOAT Factory series shocks in the XC and Trail category. Also fits some OEM Fox shocks found on major brand bikes. Wolf Tooth Low Profile Shock Rebound Knob Specifications Design and manufactured in the Minneapolis, MN USA Uses stock set screw (tiny little set screw that holds the stock rebound knob in place) Rebound is adjustable via a 2.5mm hex key (see picture in carousel) Material 7075-T6 aluminum Colors - Red Weight - 3g