General description Specifically designed to attach wood to heavy section steel (Max. 12mm), the TIMCO Self-Drilling Wing-Tip Steel to Timber Heavy Section Silver Screws are engineered for optimal performance. The metric thread features 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 facilitate the threading process. Technical specifications Dimensions: 5.5 x 100 mm Maximum steel thickness: 12 mm