Fast, safe, and accurate ultrasonic pregnancy tester. No buttons to push! No lights to watch! Ultrasonic pregnancy detection with the Preg-Tone® is a proven and accepted herd-management technique. Uses high-frequency sound waves called ultrasound to detect amniotic fluid present during pregnancy. When this fluid is detected, the instrument produces a loud continuous tone. When used on an animal which is not pregnant, the instrument produces an intermittent tone. The intermittent tone also indicates that good skin contact is being made. No guessing and no question! Since the Preg-Tone® uses only loud, easy-to-hear tones to indicate both pregnancy and nonpregnancy, it can be clipped on the belt or kept in a pocket - it does not need to be seen or held during testing, so attention is not diverted from the animal. Rugged all-metal construction guarantees against interference by radio waves in the atmosphere. Uses rechargeable Nimh batteries (included) in a pack that will last for years and give many hours of testing on one overnight charge. Unique circuitry causes the Preg-Tone® to turn itself off when the battery needs recharging, preventing erroneous readings due to insufficient power. Battery charger included. Clinically proven 100% accurate on normal sows. Pregnancy testing in swine can begin as early as 18 days (large litters, 11-12 piglets). Open sows can be diagnosed as early as 30 days. Normal testing time in sows and gilts is 30-73 days. Can also be used on sheep, goats, alpacas, and llamas.