• 300 ohm 
• Incorporates “touch-proof” electrical connection for safety
• Duplicates ER•3A smooth frequency response
• Provides 30+ dB external noise exclusion - equivalent to a single-wall booth when used with deeply-sealed foam eartips
• Provides 70+ dB isolation (interaural attenuation) between ears; reduces the need for masking
• Reduces test/retest variability compared to supra-aural earphones
• Eliminates test errors due to collapsed ear canals
• Simplifies RECD (Real-Ear-to-Coupler-Difference) measurements
• May be calibrated in a 2-cc coupler, occluded ear simulator, or 0.4-cc coupler
• Uses E-A-RLink insert eartips 

NOTE:  This is a special order item and may incur additional lead time