Mastolab-100 has Drostanolone Propionate as active substance and is an anabolic and (low) androgenic injectable steroid.
Probably you heard about it under the trade name - Masteron.
Mastolab-100 (Drostanolone Propionate) is mostly used by bodybuilders who are on a diet and want muscles growth with no water retention and possibly reduction of body fat.
This product can increase muscle hardness and density.
Masteron is a derivative of DHT (dihydrotestosterone) and does not convert to estrogen via aromatisation.
Since this is Propionate version it will be injected EOD.
The normal and working dosage is about 200-500 mg/week and cycle length in most cases is from 6 to 12 weeks max. That dosage and lenght is enough to get results. Surely all other aspects like nutrition, rest, workout must be taken care of as well.
It is often used with Testosterone Propionate, Primobolan either Winstrol or Anavar.