I have a 45 mm rotary cutter and the blades fit extremely well within it. They are not loose and while in use, they move smoothly. The holes this crochet edge skip blade made were very good not too big. After just one pass on my self-healing mat, they gave me the results I needed. Overall it's a fantastic replacement blade that is just as compatible as the original manufacturers in my opinion.
I love the quality of these blades and will definitely be ordering replacements by the same company next time!
To buy on Amazon: http://amzn.com/B01D1X0W2I