1/4 In. X 12 In. Cobalt Aircraft Extension Drill Bits, Plastic And Wood VALYRIANTOOL Cobalt Drill Bit Aircraft Extension Long Deep Hole drilling for 6 Inch or 12 Inch Overall Length: 3PCS 1/4" Cobalt Drill Bits: 3PCS - 1/4"(Drilling Diameter) x2-3/4"(Flute Length)x12"(Overall Length) Metal Drill Bits. This drill bit fits the majority of power drill currently on the market M35 Cobalt High Speed Steel: Industry grade M35 high speed steel drill bit set, harder than 4241 HSS used in other similar drill bits set. These drill bits also contain 5% Cobalt, which increases wear-resistance and durability Fully Ground Process and 135 degree Split Point: Fully ground spiral groove design clears particles quickly, decreases friction and heat for a faster and cooler drilling performance. 135 degree split point with straight shank prevents walking and makes drilling precise and faster. No center punch is needed Multiple Application: Perfectly suitable for cutting through Hard Metal such as Stainless Steel, Steel, Sheet Metal and Cast Iron as well as Plastic, Aluminum Alloy, Wood and Other Softer Metals. Pay attention to speed, pressure and heat control during drilling 90 Days Warranty: If you are not fully satisfied for any reason, please contact us for 100% refund or replacement