1. Dewalt
DCF899(I~III档正向力矩约150/400/900，反向200/440/1025)5AH20V电池，20V电池其实就是3.6×5=18V，Ali上有kit可DIY：https://www.youtube.com/watch?v=0YZOXYZ1qrw。
DCK278C2 brushless combo: DCD708B 1/2" compact drill/driver 6.3", DCF809 1/4" impact driver 5.1" 141.7ftlbs。试了DCD708B可以钻水泥唯速度较慢。DCD805B似乎是最短的hammer drill，DCD740B angle drill更矮只有4"但无hammer。
2. Ryobi
3. Milwaukee
https://documents.milwaukeetool.com/54-08-1156.pdf
4. Others
Harbor 48mm， Old 73mm dia。
Hitachi DB3DL2 3.6V打滑，零件https://www.ereplacementparts.com/hitachi-db3dl2-cordless-driver-drill-parts-c-7927_13224_147578.html
