The Cygnus 1 Intrinsically Safe is a rugged shock-proof multiple echo ultrasonic surface thickness gage designed for safely measuring metal thickness to determine wastage or corrosion in potentially explosive environments. By using multiple echo technology the metal thickness gage measurements are error checked using 3 return echoes to provide repeatable reliable results. Supplied ready to use in a protective carry case with 2 rechargeable batteries the Cygnus 1 can achieve up to 10 hours of continuous testing before recharge is necessary.