A balloon formed of a single layer of polybutylene terephthalate and polytetramethylene ether glycol terephthalate copolymer in a substantially unblended form. The copolymer has a flexural modulus of greater than about 150,000 psi. The presently preferred copolymer is Hytrel® 8238 by DuPont. The balloon of the invention would be substantially unblended, defined as greater than about 60% by weight to about 100% by weight of the copolymer. The balloon is formed in a series of molds. The balloon of the invention exhibits high rupture pressure and low compliance coupled with good lesion cross and recross ability.