My 'Olfa' handle is very old; early 1980's. I just replace the blade when it gets dull. Anyway,I am very used to the way this product works, how to change the blade , ect.... not new to me. I purchased several packages from Hb. The blades do not fit on my handle.It will not roll to cut.I suppose that if I had another cutter, I could try them on another handle, but I am very happy with what I've used for many years.I can cut fabric using either hand sucessfully with my 'Olfa' and found that when I had oppertunity to use another product I wasn't as sucessful.
Whoever said, Take them back for refund, is correct.