Hello Picard,
You can use either 168A or the 168s in your Wolfeyes M90. The difference is the 168A cell is made for use in the Wolfeyes/Pila light. The ''S'' series batts can be use in some
Surefire lights and also the Wolf/Pila series. The difference is the 168A is fatter and has a bit more capicity than the 168s. Unless you have Surefire lights also and check the postings for what will work in your particular Surefire you should probably get the 168A batts. [your light takes two of them. VERY IMPORTANT...a few of the Dealers websites have incorrect info on these light as to the model names and the batteries that they use. If your new light will take 4 regular 123a batts then it is the model that will take 168A, 168s or reg 123a batts. also take off the head and make sure that your lamp assembly is marked 12v and
not 9v. I read a post about this happening.....good luck I use Pila batts and may get a light (pila/wolf) soon....william