Abstract: A flexible shaft coupling device having two hubs with teeth extending from each hub toward the other hub. The teeth are in parallel alignment and spaced from each other. A flexible elastomeric belt fills the gaps between adjacent pairs of teeth. A retainer band is mounted around the belt to keep the belt securely in place. A locating pin on the interior surface of the band is received in a J-shaped groove cut in the exterior of the belt. This releasably locks the band in place around the belt. In an alternate embodiment, the J-shaped groove is replaced with a first groove extending across the belt and a pair of oppositely extending perpendicular grooves intersecting the first groove. This configuration allows the band to be slid onto the coupling from either end.