Holman rock drill: RB (666)
this set weight 32 kg . And high percussion energy is better
than the similar ones. Is application is for breaking the
reinforced and unreinforced concertes, asphalts, and hard 
stones (hard rocks). Another model of this set has whole
parts of rock drill 6/6 as well as is equipped with oilcan.

Holman rock drill: RB (777)
This set has weight about 38-40 kg . And is used for hard
works, because its piston course is long and creates high
energy, this set is used for asphalts and reinforced and
unreinforced cocretes and also for places that explosion
is impossible.