* Ideal for MDF / all fibre boards / chipboard, matches most common board sizes. * Clamps the boards fast * Will not pull apart under load * Does not blister the board on insertion Tite-Fix MDF-Tite Tri-Lock Pozi Screw 3.9 x 40mm (200 Pack) in Gold. Once driven it will stay in place for good, will not work loose as the floor boarding is walked upon. Clamps the boards fast Will not pull-apart under load No pilot hole necessary Does not blister the board on insertion. This pack of Prodrive drive recess countersunk flat heads are constructed from a durable case hardened, 40mm in length and come partially threaded. They have coarse thread and underhead ribs. They're ideal for a range of DIY applications.