What do you mean by how many pits of electric drill?

the one upstairs is misleading! There are four electric hammer bits (two pits and two grooves) and five pits (two pits and three grooves), all of which are Bosch's patents, not Dewei's! There are also domestic square four pits and hexagonal drills! If you drill reinforced concrete, it is recommended that you use a four-edged drill bit. First, it will not jam the drill bit. Second, the life of the drill bit and the machine will be longer!