it comes in a bottle with a sponge wipe so you could always just pour it into a bigger one to dilute it. mine was a nervous wreck as a foal with spray bottles but B&Q do brilliant ones in the gardening section that are huge and you can lock the handle in the spray position so it gives a constant spray AND THEY ARE REALLY QUIET!!!
I bought 2 bottles (they are abou £7 each but well worth it) and i used one filled with just water (so i wasnt wasting my coopers) to get him used to the spray and then had my coopers in the other one. i also have one for my coat conditioner/shiner as the spray is very very fine and wide so you get an even coverage with no streaks or smeary wet lines.