Hi and welcome to the board! I still have my original Fiskars rotary cutter, 45mm blades. I learned the hard way, only buy name brand blades from Walmart, Joanns, Hancocks, etc. Notice the center opening in those cheap blades, they don't fit the cutter correctly, and in the case of blades, you get what you pay for, IMHO. And I'm a cheapo, look for bargains like everybody else, try to find the sales and use coupons for best results.