Concept 2 Storage. The storage unit simply slides over the frame. Medium L x W X D - 105mm x 95mm x 75mm Large L x W x D - 105mm x 145mm x 75mm Shoe Storage on the back of each box if selected. Concept 2 Bike Erg Storage Solutions£19.99PriceSize*SelectShoe Holder*SelectQuantity*Add to CartBuy Now