Carefree Clearwater, and Caribbean Clear units, Old Clearwater Pool model R-150 electrodes 

2” threaded plug with 3” long electrodes. Carefree Clearwater models 1100, 1200RHR, 1200R and Caribbean Clear units, and our old R-150 model from the 1990s (the R-50 unit will lose the temperature readout capabilities). 3” long, 1 ½” “half-moon” in diameter sealed in a threaded 2” plug, Schedule 40.    Price includes free shipping in the USA.