BOSS PH-1R Phaser Silver Screw The PH-1R Phaser is an improved model of the PH-1 Phaser, BOSS's first phaser, with the addition of a RES control for greater practicality. RES stands for Resonance, and it is a knob that controls the amount of feedback in the newly incorporated feedback circuit. Body only * Operation checked, cleaned, and in perfect working order. --------------------------------------------------- Thank you very much for viewing this product! Please feel free to comment if you have any questions. (If you are negotiating the price, please provide your desired price.)