I use both switch cutouts on mine. Left is bilge, right is TL on/off. The Blowsion switch fits, but is NOT the switch you want. Riva has the one you want. More expensive, but lasts forever. They look the same at first glance, but the one Riva sells is vastly superior. On the good one the raised rubber cover looks like the number "8". Both are made by CPI. Here is a of pic of mine.