To adjust the cut-in pressure 

1st you have to change the Com Box from MONITOR mode to SETUP Mode.

to do this press the Reset/Select Button and the down / - Button for 3 seconds until the red and green LED's flash

then you can use the Up/+ to increase the cut-in or use the Down/- to reduce the cut-in.

then press the Reset/Select Button and the down / - Button for 3 seconds until the red and green LED's stop flashing