Tubular aluminum rack is disc brake compatible. Fast, easy mounting of BabySeat II without use of tools. The MTX QuickTrack plate is compatible with any Topeak MTX TrunkBag, MTX rear basket, and MTX 2.0 TrunkBag. ATTACHMENT: Braze-on type MATERIAL: 6061 T-6 hollow aluminum COMPATIBILITY: MTX QuickTrack & MTX 2.0 QuickTrack systems MTX TrunkBags, MTX rear baskets & MTX 2.0 TrunkBags MAX WEIGHT: 27 kg / 60 lb CAPACITY: Meets EN 14872 / ISO 11243) ADDED FEATURES: Includes mounting bracket (26.5 cm), Solid fender top, RedLite Mount, Tail Light Mount. Designed for 26' 27.5' 650B and 700C Wheels w/ disc brakes. Size 40 x 34 x 23 cm / 15.7” x 13.4” x 9”. Weight 630 g / 1.38 lb.