The Armeg Acceler 8% sheet-metal hole saw is designed for speed. According to the manufacturer, the bit is 37% faster than the standard metal hole saw. This is due in part to a thin kerf that reduces resistance. The teeth are made from high-speed steel with 8% cobalt, so they are able to handle high drilling temperatures and constant use. The body of the saw flares out at the base to prevent the drill from fully entering the hole once it is cut, and a spring around the centering drill bit automatically ejects the slug. It’s available in 14 mm to 38 mm sizes individually or in kits. Price: Starting at $25. +44 (0) 1246 411 081. armeg.com.