Don't waste your money
I've never heard of anyone, and I repeat anyone, that's had good luck geting the high-capacity, detachable magazines to work reliably. Learn to load from stripper clips, its just as fast.
Or, if you MUST have a hi-cap SKS, find an SKS-D or SKS-M, which take AK magazines. My SKS-M works flawlessly with every AK mag I've ever used.