Is it a straight razor? Or do they use some other razor bladed device? I think I saw a product called a razor comb....

I have another question too:
I saw something online about trimming up bangs between visits as well... it said to use a single bladed razor and not one with double of triple blades... does that mean they were recommending using disposable razors like you would shave your legs with to trim up your bangs??

I've always had layered hair and I prefer it to be more choppy... but my hair needs updating BAD! This time i want to try to have someone razor cut it... a lot of people do it themselves at home... I'm not one to ever have good luck when someone else cuts my hair...

So what would I use if I wanted to do it myself??