Bug sinkers are ideal for estuary and lake fishing where a light, low profile lead is preferred. They are often used in a running sinker rig, where the main line is threaded through the sinker and left unattached, so it can move more freely, usually positioned either running directly to the hook, or restricted to running along the main line above a swivel connection. Unlike small ball sinkers, the bug sinker's flat sides make it less prone to rolling along the bottom in current. Use a bug sinker when water flow is a little too fast for split shot, but not so fast as to require something heavy.