I hear they are hydraulic brakes on unicycles, but why wouldnt a linear pull brake work? THanks
Much the same reason why most people prefer a word processor over a manual typewriter! One is much more efficient and precise, and yes, costs more too! And although they will both get the job done, you would definitely feel the difference. Too some, that difference may not be worth the extra cost. 
Hydraulic rim brakes are very compact and out of the way making them less likely to get in your way while riding or crashing into stuff like trees. I’ve tried linear v brakes and side pull brakes and they don’t provide as easy or predicatable braking as the hydraulic brakes. I have lots of used ones if you are interested in a lower cost used hydraulic brake. I have some that are in the $50 range. PM me if you are interested.
Brycer
Hm, I would like to, but I just got my muni yesterday so Im a bit short on the cash
I think one of the main reasons that Magura hydraulic brakes became popular on unicycles, apart from the leg-hitting thing that Brycer mentioned, is that a v-brake won’t easily clear a 3" tyre, which people like to use for muni. With a hydraulic brake you can just fit a longer crossover hose and clear any size tyre you like.
Not trying to take anything away from Brycer (the brakes he sells are in pretty much as-new condition), but you can pick up used HS33s pretty cheaply on ebay. If you buy a bike set then sell all the bits you don’t need they can work out really cheap if you don’t mind a bit of cleaning and rebleeding. I’ve done that twice now and ended up with one brake costing me £4 and the other about £8 
You still need the 4-bolt clamps and something to attach the lever to the unicycle, but it doesn’t work out that expensive.
(I paid about £50 for a set of HS33s on ebay, then sold one half of the brake for £25, the boosters for £6 and the Evo mounts for £15, leaving me a brake for £4. With the other one I didn’t get quite as much for the mounts and booster).
Rob
i wouldnt really want to do yours no offence =) buying and selling isnt really for me. Id pay extra for convenience =) THanks everyone
I’ve had my KH24 with maguras for just over a month. I had never used a brake on my uni before this, and I’m loving it.
For me, the most difficult downhills are tight turns with roots and rocks. I need to grip and control my seat while simultaneously modulating my brake with one hand. The hydraulic brake is so sensitive and smooth, it makes braking with one or two fingers a breeze.
I’ve never had a cable brake that worked as well on my b*kes.
Yup, Rob is right-on with this - and I’ve gotten some of the brakes I sell here this same way and you can make out pretty well if you have some basic brake bleeking skills and a bleed kit. The bummer is the 10-20% of brakes that I buy this way that leak or are not functioning because few folks know much about these brakes. I end up putting the broken/leaky parts in the scrap metal bin and using/selling the stuff that is still in good condition . . . . and I’ve gotten better at sleuthing out which ones are likely to be leakers, but its totally easy to get burned with used hydro brakes.
A couple of key things to look for going the e-bay route:
- Don't by brakes from bike trials riders. They tear up brakes faster than any other hydro brake user.
- Don't buy a brake that has been bled with water or antifreeze. It rusts the springs and the brake wears out much faster.
- Avoid the knock-off brands like RB design and Echo. They leak a lot.
- Worn/mashed down slave cylinder resin rings are a good indication of the abuse the brake has seen and over all condition.
- Used brakes should be thouroughtly flushed with fresh Magura fluid before bleeding it.
- Slave cylinders are not repairable. Once they leak, they have to be replaced.
- Brake levers that leak are usually difficult to repair and replacement pistons/seals are super hard to find.
- Don't EVER expect a seller to give you any clear answer to questions about leaking brake slave cylinders. Small leaks are hard to detect and look more like a black grease under the brake pad, but rarely show drips and such that most would describe as an actual leak. I test all the slaves I sell under full pressure and scrap the ones that leak or have notchey or uneven deployment.
- If you buys a brake branded with "move" "blue" or HS11, HS12 or HS24, they will come with plastic lever bodies that are just fine for most uses including unicycling, but will be slighlty less durable than the metal lever bodies found on the HS22 and HS33's.