STAB is a new edge-based probing tool to locate thin links on an end-to-end network path in space and over time. Thin links are those links with less available bandwidth than all links preceding them on the path. STAB uses special chirp-probing trains that allow accurate estimation of available bandwidth using few packets. Thin-link localization helps network operations and troubleshooting, provides insight into the causes of network congestion, as well as aids network-aware applications. The authors review the current state-of-the-art available bandwidth tools, describe the working of STAB, and validate it through Internet experiments and simulations.