The DigiDop 301 rechargeable, non-display Doppler's most unique feature is Digital Optimized Processing (DOP™). DOP™, unique to the DigiDop, allows the fetal or vascular sounds to be amplified while also suppressing the background noise typically found with Dopplers. Each DigiDop is designed not only with the sensitivity you need but also the toughness and durability to last through years of everyday office use. We believe that so much we offer a comprehensive 5 year warranty - all labor & all parts, including probes and cords. All our products are Made in the USA near Denver, CO. Each Newman Medical Doppler and probe must pass a series of comprehensive tests to assure quality and the durability of each product. Incredible sensitivity - up to 6x other Dopplers Unlimited 5 year warranty - ALL parts! All labor! Smart Recharge System - don't blow up alkaline batteries again!