Wrong description on the package
I used the starter according to the instructions on the back side and I wasted 3 of the packs. None of them worked. On the back side of the package it was written that 73-77 F.  At this temperature to incubate is impossible. For the 4th pack, I tried 112 F and it worked perfectly. In the end I wasted half of the packs!!!
Rating: 2 stars