It is made of high strength S2 alloy steel, very durable. Hardness is good, hard to break and wear resistant. Magnetic drill bits, in the installation can easily absorb the screws. Suitable for installation in pneumatic screwdriver, electric screwdriver, Rechargeable drill, using the wind lot. Widely used in power tools, electric screwdriver assembly, electronics industry, household appliances, precision instrument industry, screw equipment of furniture industry. Specification: TA18 the height of the middle triangle is 1.8mm TA20 the height of the middle triangle is 2.0mm TA23 the height of the middle triangle is 2.3mm TA25 the height of the middle triangle is 2.5mm TA27 the height of the middle triangle is 2.7mm TA30 the height of the middle triangle is 3.0mm Size Chart: Size: Approx. 100x68x6.4mm or 3.93x2.67x0.25inch Package Includes: 12 Pieces Screwdriver Bits Note: Please allow 1-3mm measuring deviation due to manual measurement. Due to the different monitor and light effect,the actual color of the item might be slightly different from the color showed on the pictures.