The most common sensor we do - This is a single M7 heater sensor.
We have varying lengths but the most common by far is the 24 inch variant - 95% of the market is covered by this sensor
There are two Balboa M7 system heater sensors located at each end of your heater and are identical to each other.
We do not sell the sensor mounts with the sensor as it is extremely rare they have perished, if you need the mount you can find it here though
The 24" inch sensor replaces sensors marked 30382 & 30344
Wellis P/N: ACM0652