I'm using a JC in my glass enclosure and i have the probe between the flexwatt and the glass so that it gets an good reading. I loose about 1deg because of the small air gap but at least i know its not getting too hot. SP or S1 stands for the set point and would be the temp you want it to try and keep on the warm side, mines set to 93deg. DIF is differential temperature this is the tolerance for temperature fluctuation before the thermostat clicks on and off the smaller the number the more steady the temps will stay, mines set at 1. The C1 and H1 selects the mode (C1 for cooling H1 for heating).

Heres the exact instructions that came with mine

Step -1

To start programming, press the SET key once to access the Fahrenheit/Celsius mode. The Display will Show the current status, either F for degrees Fahrenheit or C for degrees Celsius. Then press either the Up or Down arrow key to toggle between the F or C designation.

Step -2

Press the SET key again to access the setpoint. The LCD will display the current setpoint and the S1 annunciator will be blinking on and off to indicate that the control is in the setpoint mode. Then press either the up key to increase or the down key to decrease the setpoint tot the desired temperature.

Step -3

Press the SET key again to access the differential. The LCD will display the current differential and the DIF1 annunciator will be blinking on and off to indicate that the control is in the differential mode. Then press either the up key to increase or the down key to decrease the differential to the desired setting.

Step -4

Press the SET key again to access the cooling or heating mode. The LCD will display the current mode, either C1 for cooling or H1 for heating. Then press either the up or down key to toggle between C1 or H1 designation. Press the SET key once more and programming is complete.

hope this helps