I use these blades in my very old, gray fiskars cutter...best price I've found too:
https://www.quiltedtwins.com/shop/c/...-x50943313.htm
actually I have tried many different blade brands in that cutter, and most will work.
I just bought these bcuz I wanted to try titanium:
https://www.amazon.com/s?k=rotary+bl..._ts-doa-p_3_14
You might notice that amazon does sell 60mm fiskars blades....listed on the same page as the link above