Our Best Seller Nunn Finer Running Martingale with Elastic has the perfect amount of give. Premium supple oiled bridle leather is made to last through every day use. The double layer of German elastic has just enough give. Roller Buckles. Available in havana or black leather with zinc or brass fittings. Fittings: Zinc, Brass Sizes: Cob, Horse, Oversize Colors: Havana, Black