The side siteboard holder is made of and strong aluminum,this surfboard rack 't rust or corrode.The surfboard bicycle carrier rack with humanize design,which can prevents your bike and board from rubbing.This bike skimboard is suitable for most bicycles models, Such as Beach Cruisers, Road Bikes,Mountain Bikes,BMX Bikes,not recommended for seat posts.ESSENTIAL SURFBOARD BIKE RACK - Essential Surfboard Holder, Explore the freedom of biking with our convenient Surfboard Bike Rack.HASSLE-FREE INSTALLATION - Experience hassle-free installation with our innovative bike surfboard rack ebike! No need to remove your bike seat - simply screw mount directly to the seat tube/down tube.Colour:BlackMaterial:aluminumPackage Contents:1 * surfboard standOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.