Sennheiser HDR 175 Additional Headphones for the RS 175 System featured it cancels far more noise

it cancels far more noise across the frequency range than a passive product

Standard feature model: SONOROUS X

Auto video and source selection

Tactile main control knob

look and touch

Sennheiser HDR 175 Additional Headphones for the RS 175 System featured it cancels far more noiseMust have RS 175 before buying HDR 175! Closed back, circumaural headphone system High quality Sennheiser transducers for exceptional sound Designed exclusively for use with the RS 175 RF Wireless Headphone system (sold separately) Two year warranty when purchased from an authorized Sennheiser dealer. Must have RS 175 before buying HDR 175 Additional replacement headphones for the RS 175 digital wireless headphone system. Features Closed, circumaural