A stabilizer comprises a body having first and second ends, each of which is formed with a respective connector means, the body having an outer wall upon which is formed a plurality of the upstanding blades radially outer surfaces of which define gauge pads, flow channels being defined between adjacent ones of the blades, and at least one bridging region interconnecting two adjacent ones of the blades to form an enclosed passage communicating with an associated one of the flow channels, the bridging region having a surface defining part of an outer gauge surface of the stabilizer, the at least one bridging region being located intermediate and spaced from the first and second ends.