Smoothing Air Hammer Tool Kit Pneumatic Chisel Bits Accessories Including 3pcs 0.401'' (10mm) Shank Air Hammer and 1pc Spring Features: Material: alloy steel Type: hammer bits Sizes: -- Oval-shaped Air Hammer bit: 176 * 25mm (6.93 * 0.98 inch) -- 2 Pcs Flat Head Air Hammer bits: 100 * 30mm (4.0* 1.18 inch); 80 * 35mm (3.14 * 1.37 inch) -- Spring: 28* 26mm (1.10* 1.02 inch) Package included: 3x Hammer bits 1x Spring Note: 1. Please allow 1-2cm errors due to manual measurement. 2. The head of the hammer bits includes convex and flat head. 3. Due to different image angles, some images may not clearly display the head shape, please understand, thank you! 4. The bit installed in the pneumatic sewing machine needs to be connected to an air compressor for use and can be replaced as needed.