Loading... Please wait...2" Spa Heater Split Nut - serves same function as the Aquatemp Uni-Nut, however suits older style Aquatemp, and all Balboa, Gecko Electronics, and some other heater tubes with flanges to wide in diameter for the 2 part nut system above. The nut has a built in collar to prevent it sliding off the tube. This nut is in 2 halves held together by 2 screws, however once assembled over the tube, threads on and off the union tail without the need to undo the screws.