19inch fixed vented rack shelves are fitted into the rack using M6 Cage Nuts which need to be purchased separately. The fixed vented shelf is 485mm wide and will only fit into racking of this width (measuring between the side holes, not front holes). This product is designed for use with Orion rack cabinets and if you want to use this in another type of rack please measure to make sure it will fit as this is a made to order item. The shelf is designed to support up to 25kg maximum. The shelf is also available in a heavy duty (HD) version which is designed to support up to 60kg maximum.