Hey, brother, they are actually the same product. Serono International is the manufacturor of both Serostim and Saizen kits. The Serostim is simply more concentrated......for patients with wasting diseases like AIDS. One ml. reconstituted = 18iu. Saizen is marketed for hormone replacement therapy, like for old guys such as myself. One half ml. reconstituted = .75iu only.
Generally, Serostim kits are a much better buy on the black market.
I've used them all, including cadaver extract.