Gymboss PLUS model timer - Louder beep. Increased water resistance. Targeted towards outdoor activities. Perfect for run walk run programs, interval running training, learning to run, or for users who want to easily monitor time rounds remaining during activity. Also, due to it's loud beep capabilities it is ideal for group classes. With a Gymboss timer, a minute rest really means a minute rest, and a 45 minute workout lasts 45 minutes! Maximize your training to increase: Anaerobic endurance, Muscle strength/size, Cardio endurance, Increased VO2max, and Fat loss. Gymboss - Train Hard, Train Smart.