Pre-packaged in 10 packs. 304 Stainless Steel Hex Nuts available in M2, M2.5, M3, M4, M5, M6, and M8 sizes.
I buy these bolts and nuts from 3D Printing Canada because the price cannot be beat. For me it is also super convenient as the store is 10 minutes from my home. I use them for various projects that have nothing to do with 3d printing.
They're hex nuts. They're steel. They're smooth.
Not much else to say - they do what they're supposed to do and they're fine to handle.
Excellent assistance from the staff.