I did buy mine in a set; it was on sale and I am a notions/tools fool. I LOVE them. I have used a larger one when smaller one wasn't readily available (ie, buried under a pile of stuff...), but honestly, it is easier to use one that is the correct size, or close to it. I will admit that I've never used the 6.5" one as I rarely have hst's that large. If buying one, I'd go with 4.5" before the 6.5".