Pull buoy, or leg float. Must have bought this around about 1986, and used it for hundreds of swimming miles. The return to the pool after a near two year gap was seeing a slow improvement, but the dicey icy weather has curtailed that for a while. In the game of snakes and ladders that is fitness and health, it's like hitting another snake, taking you back a stage. That two year gap was a return to the very start. The few ladders are very short.