Batch head: 17, 19, 21mm. Square head nominal size: 12.7 (mm). Impact number: 0-3300 (ipm) drive shaft / chuck drive. Replace DGA504, DGA506, DGA404, DGA402, DGA406, DGA450, DGA452, DGA454, DGA456 and stand to Makita BL1840, BL1840B, BL1850, BL1850B, BL1860B. DGA504, DGA506, DGA404, DGA402, DGA406, DGA450, DGA452, DGA454, DGA456. Compact and lightweight: It is much lighter than others, weighs only 1.8 kg after installing the grinding wheel, but no battery to reduce fatigue during operation. If item is defective after 3 months, you can still send it back to us.