As a horse owner for over three decades, I've gone through my share of clippers. Equestrians know that you need to clip your horse even if you're not showing. Horses look tidier when you trim their whiskers, and it's easier to put on a bridle when your mount has a neatly clipped bridle path. Oster makes a variety of clippers to meet pretty much any horsey need.
Heavy Duty Clippers
I tested two different types of Oster clippers, Oster Outlaw 2 Speed Clippers and Oster Cordless Trimmers. The Oster Outlaw is a heavy duty model meant for tasks like roaching a thick mane or doing a full body clip. This model has the "oomph" to clip through thick hair with no problem.
That power comes with a price, in the form of a somewhat loud motor. That's fine if your horse is totally desensitized to clippers. I tried these clippers on several horses that are used to being clipped with buzzing devices and had no problems.
My horse Figment is sensitive, so he wasn't too thrilled with the sound. I made sure to spritz him down with fly spray before our clipping session so the bugs wouldn't give him an extra excuse to be antsy. He let me use the clippers on his muzzle, but it took some cajoling. I used them on his legs, too, and that didn't bother him much at all, since he couldn't hear the sound as well when they weren't near his face. He wasn't at all keen about having them anywhere near his ears, which is necessary for properly trimming a neat bridle path.
Cordless, Quiet Clippers
Enter the Oster Cordless Trimmer model, which you can use with or without an electrical cord. These clippers are much quieter than the Oster Outlaw and easy to maneuver if you charge them up and use them in cordless mode.
It was easier to calm Figment when I wasn't encumbered by a cord. He was also less reticent to let me touch his ears with these quieter clippers. Even though they're not as powerful as the other model, they have a good amount of clipping ability to get the job done. It's a worthwhile trade-off between high power (and the sound that goes with it) or less power but quieter operation.
Cordless clippers have another advantage in a barn besides maneuverability. As long as you keep them charged up, you don't have to worry about being close to an electric outlet. This also makes them idea for quick touch-ups at a show, even if you're not near a power source.
Both sets of clippers come with helpful accessories. The Oster Outlaw clippers and the Oster Cordless Trimmer each provide you with a cleaning brush and oil. I'm sometimes lazy when it comes to cleaning my clippers after every use, but it's a worthwhile time investment. The included cleaning tools take away my excuse for being negligent. The Oster Outlaw clippers run around $165 and the Oster Cordless Trimmer costs about $35 to $45. That's enough money to motivate the typical equestrian to keep them in good working order.
The Outlaw clippers also come with a nice little soft-sided carrying pouch that holds all the different parts. When you tuck everything inside, it fits right into your tack box without taking up a lot of room. In addition, you get a mane and tail comb, a step-by-step DVD, and two additional blades.
A Grooming Necessity
Just as a good shedding tool like the FURminator or the ShedMonster is a necessity for small animals, a good set of clippers is indispensable around the barn. Whether you need the full power of the Oster Outlaw clippers or can get by with the Oster Cordless Trimmer depends on your personal situation.
If you ride mainly for pleasure and use your clippers primarily to keep your horse's bridle path trimmed and to keep him looking presentable, the trimmer should fill the bill. If you're into showing or need to body clip your horse, you'll want the heavier duty capabilities of the Outlaw.