The Finlandia / Harvia Part # F40-O Timer Knob is designed specifically for sauna timers or thermostats with an oval-shaped shaft, providing precise control over your sauna's settings. This knob is compatible with the Blue and White series of Finlandia and Harvia control units, ensuring a secure fit and easy operation. Its durable construction makes it a reliable replacement part, helping to maintain the functionality and ease of use of your sauna's control system.