There are a couple types of carpet cutters. The one I bought was school bus yellow with one blade in the cutter and a couple extras, for 2.99 if I remember.

I order mine on the computer - harborfreight.com - for $1.49/pkg of 2 blades.
Since shipping is a bit high, I ordered 10 pkg for same shipping rate as if I had ordered 1 pkg, & its still less than local blades @ JoAnn's or LQS.
They fit my 45 rotary cutter. I like the blades & don't feel badly tossing them if they get dull.
montanajan

At my store they are 2 blades in a little plastic bag sort of taped over with a hole on the top to stick on a rack. Once I found one that had a cardboard label.

It's really easy to overlook and some stores don't get them in often. Or get very many when they do come in. I'd call to make sure they had some before making a trip if it's a special trip. I just stop by when I'm at the grocery store next door.

I've been thinking about buying the actual carpet cutter and just throwing away the yellow plastic thing. But that seems so wasteful...but hey $3 for 3 blades, not really in the whole scheme of things.

what is the brand name

I have used the harbor freight, sometimes they cut really good, other times not. I was wondering if there's a correct way to cut with a rotary ? blade on angle or straight up??which might make a diffrence in the way it cuts.

Been using them for a while & have no problems

I think always the rotary cutter should be held straight up & down, not at an angle when cutting. You get a cleaner cut that way. And when cutting several layers at once, if you cut at an angle, probably the pieces won't be precisely the same size.
Perhaps some blades might not be as sharp as others. The package says these are made in China, if that makes any difference. I just got my HF blades & the first one is great! Really sharp & cuts cleanly. Just what I want.
mloquilts

I'm using the Harbor Freight blades too. they are lasting me as long as the olfa blades. I have been cutting my batting as well as fabric with them. If they get to skipping after cutting batting or paper, just run them through some folded up aluminum foil a few times and it will cut just as good as new again.

Good Luck

Suzy

Wow Suzy, what a great suggestion! I learn something new each day from this board.

I've read that they work in an Olfa rotary cutter but will they work in the blue Dritz rotary cutter?