EDIT: I'm so thrilled, I found a way to have only the beep, and omit the crazy creepy voice!!!! I thought my clients could just watch their own timer, and not have the sound, but after getting them conditioned for so long to the beep on the GymBoss, some of them still wanted the beep. FYI - Turning down / off the volume is not the same setting as omitting the voice. So I have 3... getting ready to order #4. Love this timer.Original Review:I own a gym & am a personal trainer. I’ve used GymBoss timers for 14 years; however in beginning to go to semi-private training, where I’m training 3 clients at the same time, I needed silent timers & ones they could easily see.For me, being portable, having a rechargeable battery, having the option for custom intervals, being able to set program it on the unit & not with a remote control, and to be able to turn off the sound were all dealbreakers!!! This timer checked off all those things for me!!I just got two programmed & will program the 3rd one tomorrow. I’m extremely happy with these timers!!!NOTE: For all the naysayers who are commenting that these are very difficult to program…. You’re wrong!!!I’m 55 & had no trouble at all. All you have to do is follow the instructions. If anyone has programmed a GymBoss you can definitely program this unit.