Disposable Poly Bailers are constructed using 100% pure virgin polyethylene. Strict part and production requirements have virtually eliminated leaking and the large open-top design allows nearly an inch of open space for easy tie-on. The bailer has a thick, rigid construction and will not warp or collapse. By using a PVC ball and a steel weight triple-coated with Teflon-based non-chip paint, your sample stays securely in the bailer. A Double-Check Valve Bailer (also known as a point-source sampler) allows sampling of a specific depth by utilizing a check valve at both the top and bottom of the bailer.