Replacement connecting joint between the conrod and treadle rail used on Ashford wheels made since the mid 1980s. Clear polycord. Over time these turn sort of yellow and get brittle. One of the most common replacement parts we sell.
This may or may not fit other brands of wheels, it might be the wrong diameter or be too long, which you can change by cutting some off with a very sharp knife. Approximately 7cm long.