The 657 features:

- Amplifies up to 16x (24db) over traditional acoustic scopes
- Patented piezopolymer film contact microphone provides wider frequency response than acoustic mikes used in competing models
- Three frequency modes:
Bell (15-200Hz) for cardiac sounds
Diaphragm (100-500Hz) for lung sounds
Extended Range (15-1000Hz)
- 8 level volume control
- Holds last mode and volume setting for convenience
- Auto-shut off after 3 minutes extends battery life
- Battery warning LED signals when replacement needed
- Binaurals fixed at 15º angle for snug aural fit
- Specially constructed ADSOFT™ PVC eartips for the ultimate in wearing comfort and acoustic seal
- Lightweight and compact, measures 28” / 71 cm
- Uses "AAA" battery (included)
- 2 year warranty