For the life of me I can't think of the brand name of my Dehorner, I got a cordless electric model last year and used it on my calves for the first time this spring.
It's black and plastic and comes with a 110V charger, I used the same model years ago when I worked for an outfit back east.
It's designed to be used on small calves, the directions say to use from 7-15 days old which works for me, It's easy to catch a small calf that age and just quickly dehorn them. Although I did use it on some much larger calves that came at the side of recip cows and it appears it has worked just fine. The iron is cold until you press it down and hold it over the horn bud, after a few seconds it will start to smoke and will beep when it is gotten hot enough and you are done, I often scrape the cap off with a pocket knief and they reapply for good measure. I believe it's supposed to do 30 horn buds on a charge (so 15 calves)
Mine looks similar to this one except it's black, I think it's called "Buddex"
http://www.valleyvet.com/ct_detail.html?pgguid=2e87c05b-7b6a-11d5-a192-00b0d0204ae5
I've also used the 110V models and always had a couple different sizes at home.
One of the easiest dehorners for small calves is to just take a short piece of 3/4" pipe (or whatever size your horns are) and weld it to a rod with a T handle welded to the end, stick it in your branding pot witha Tiger torch blowing on it for a few minutes and voila, instant dehorner.
For the very few horned calves that I have a year though the cordless electric way is Slick.