A readily burstable slide fastener for an inflatable device, such as a lifejacket, includes a first stringer, a second stringer and a slider slidably mounted on the second stringer. At a weakened region along the slide fastener coupling elements are omitted from each of the stringers so that when a bursting force is applied to this region the coupling elements adjacent thereto are disengaged. Coupling elements are omitted from the top of the first stringer so that when the slider is at the top of the coupling elements of the second stringer, the first stringer can disengage from the slider. When the slide fastener is fitted to an inflatable lifejacket, the stringers are separated completely when the lifejacket is inflated.