General description Specifically designed to attach wood to metal (max. 4mm), the TIMCO Self-Drilling Wing-Tip Steel to Timber Light Section Silver Screws feature a coarse self-tapping thread with wings that ream out the timber, allowing the screw to achieve maximum revolutions per minute (R.P.M.) without burning out. When the wings contact the metal, they break off to permit the thread to engage effectively. Technical specifications Dimensions: 4.8 x 38 mm Material: Steel Type: Self-drilling wing-tip screws