I haven't used an Oster b4, but have heard that they are very nice quality clippers that last a long time. The interchangeable blades are great, you can get the desired length of cut. Just remember for blades, higher the #, the shorter the cut.
I use Andis clippers & the blades start w/ a # & end w/ 'FC'. So Oster blades must start w/ 'A'? Or is this human clippers?
I made a thread awhile back in the grooming forum. Some of the links might not work or it might not be on special anymore but you can find all the grooming supplies on PetEdge(dot)com.
http://www.yorkietalk.com/forums/yor...room-home.html