INTRINSICALLY SAFE HEADSET - A UNIVERSAL-FIT HEADSET FOR USE WITH MOBILE OR PORTABLE RADIOS IN EXTREMELY NOISY AREAS - CERTIFIED "INTRINSICALLY SAFE" IN HAZARDOUS ENVIORNMENTS WHEN USED IN COMBINATION WITH I.S. APPROVED RADIOS - NOISE- CANCELLING, ELECTRET MICROPHONE - UNIVERSAL FIT WITH OVERHEAD NYLON STRAP TO PERMIT USE OF SAFETY CAPS AND HELMETS - SOFT, FOAM EAR SEALS - EARPHONE: DYNAMIC H-143/AIC - FLEX BOOM ADJUSTABLE FOR LEFT OR RIGHT MICROPHONE PLACEMENT - SHIELDED CORD-36" STRAIGHT - PART NUMBER: 40416G-07 - MODEL NUMBER: H6640I