Produce well conditioned athletes as Cuba and Russia have through interval training. Round length adjustment - rounds can be set for 2; 3; or 4 minutes. Rest period length adjustment - rest period can be set for 15; 30; 45; or 60 seconds. Interval length adjustment - interval length can be set for 15; 30; 45; or 60 seconds or no interval. One tone indicates the beginning or end of round; another tone indicates the interval. Comes with 1 year limited warranty.