For S, M size framesThe newly designed, extended, and widened version of the MTX BEAMRACK is better suited for 29" MTB and gravel bikes. It features an MTX QuickTrackA(R) panel, compatible with MTX 1.0 and 2.0 system bags and baskets. Flip the panel to adapt it for bags and baskets from other brands. Material Aluminum Clamp Fits ;25.4 - ;31.8 mm seatpost (shims Incl.) Max load 9 kg / 20 lbs Compatibility TOPEAK MTX 1.0 / 2.0 Bags and Baskets Size 55.5 x 14 x 9.4 cm Weight 673 g