Prong collars (also called 'pinch collars') are a series of chain links with blunted open ends turned towards the dog's neck. The design of the prong collar is such that it has a limited circumference unlike slip collars which do not have a limit on how far they can constrict on a dog's neck. The limited traction of the martingale chain combined with the angle of the prongs prevents the prongs moving close enough to pinch. The collar is designed to prevent the dog from pulling by applying pressure at each point against the dog's neck.
Limit , Open and Championship Shows are run ‘by the Kennel Club’ and ‘Under Kennel Club Rules’. Each Show will have a ‘Closing Date’ for entries a few weeks before the actual event, which means you must pre-book your place, and pre-pay your entrance fee. Classes at these Shows are known as Pre-Beginner, Beginner, Novice, ‘A’, ‘B’, ‘C’, and Championship ‘C’ (in ascending order of ability / experience), and the ‘Tests’ to be performed for each of these Classes is predefined in the Kennel Club rules. In general you have to win twice in a lower class to progress on to the next level. Only winners of the Championship ‘C’ Class (which are only at Championship Shows) go on to compete at Crufts.