The Buckley mouthpiece incorporates stainless steel and copper rollers, the rollers may help if your horse tends to lean on the bit and or set their jaw, as the rollers are movable so they are not easy to get a grip of. They also encourage mouthing as it gives them something to play with.
Full Cheek Bits
Full Cheek bits are a fixed cheek bit, this may be useful for horses that are a bit unsure of the bit as it doesnt move around to much in the mouth, it should encourage the horse to stretch into the contact. A fixed bit would be less suitable if your horse is prone to leaning or taking hold of the bit
Full cheek bits are very useful for breaking in, or bringing on of young horses, as they help tremendously with the turning aids, and help to teach the horse to turn, the full cheek bit does not slide through the mouth as would a normal snaffle would if your horse doesnt like to turn. The bit is particularly useful for horses that nap, as the bit will help if the horse suddenly makes a dash for the gate or for the nosey horses who spend half their time looking at what they are missing whilst being in the paddock, The full cheek bit works by applying pressure to the cheek when an turning aid is asked. The full cheek bits can be used with or without fulmer loops/keepers, although many would say that the keepers keep the bit in the correct place, they also add poll pressure, so if you dont need any poll pressure then, it wouldnt be useful to use the keepers. But please be aware that the full cheek bits used particularly with young children, can be dangerous in some circumstances and if you horse rubs their head you may find that the cheek is hooked somewhere! A safer alternative for younger children is the full spoon bits as the cheek piece is less pointy and not as long.
Single Jointed Bits
The single joint puts pressure on the sides of the tongue, on the lips and on the bars due to the nutcracker. The single jointed bits also may have a head raising action so would be less suitable for your horse if they ride with a high head carriage or above the bit. Also breeds such as Irish Draughts, may have particularly large tongues, therefore having less room in the mouth for a single jointed bit as this pushes the bit nearer the roof of the mouth, also Arabs and alike may have a low palate, both of these examples may not benefit from the single jointed bits as the nutcracker action may cause brushing of the roof of the mouth.