Phillips screws for mounting fans on radiators. The special UNC thread, from the non-metric system of units, are specially designed for the radiators from the USA or United Kingdom. They form an intermediate size from M3 to M4 threads. Due to the flat, slightly larger head, the screw fits very well and can also cover larger holes that are present in the various types of orifice plates. So they have not only a constructive function, but are also optically and also later, after mounting, very nice to look at. The thread length was kept extra short, that by carelessness of the assembly of fan, screen or housing with the radiator the damage of the fins by too deep reindrehen is prevented. Nevertheless, we would still like to point out to check the length of the screw before mounting! Important: These screws should only be used in combination with a 25mm fan, because the screws for the narrower fans are too long and then damage the radiator. If a fan shroud is used with narrower fans (20mm), then of course these will fit again. Compatibility: XSPC, Swiftech and others. Technical details: Material: brass, black nickel-plated Length shaft: 30mm Thread length: 8mm Head height: 3mm Wrench size: 6mm Included in delivery: 4x Phobya screw UNC 6-32 x 30 cross - black nickel Attention: screwing in too far can damage the raditor, make sure the screws are the correct length. Not in every case these screws are suitable.