Bed frame glides are an attractive low profile (80mm high) option to permit easy movement of your bed.  Manufacturers use at least 3 different thread sizes on their bed frames including 5/16", M8 and 3/8".  Our Replacement Bed Leg Glide 80mm is based on the traditional 5/16" thread size.  Your bed may already have this size Insert Screw or T/Nut fitted on the underside of your bed as it has been the industry standard for many years.  If not, you must fit a matching 5/16" Insert Screw (provided) that can be retrofitted to the underside of your bed frame in place of your existing fitting. To use our Wheeled Castor Furniture Legs for Beds you must have a 5/16" thread to receive the threaded rod - no other thread size will suit. To fit the 5/16" Insert Screw (comes with wood thread on the outside / 5/16" metal thread on the inside) you will need a 10mm drill bit and may need to drill a new hole alongside the existing one.