Step Bits or Uni-Bits

What are step bits or uni-bits? Are they the same as reamers?

I have some cobalt bits that warn against using to enlarge a hole. It says to use a reamer for that. I cannot find any "reamers" in any hardware or auto parts store.

Thanks...

A uni-bit is a cone shaped drill bit that is steped and used primarily for making holes in sheatmetal.

MSC has reamers galore.
Try MSC DIRECT, or click there from the banner on my web page.
The uni bit will not make a clean hole, and only cuts about 1/8" before it goes to the next size anyway.
Many knifemaker supply houses like TKS have reamers too.
TKS has a banner to click on at the main page of CKD.
What size hole do you need?