Large, easy-to-read 3-1/8" (80 mm) steel case red and blue,1% accuracy (Class 1) gauges; front access for easy fieldrecalibration; optional protective gauge boots available Proven, double "O"-ring piston for reliability and long service life Exclusive 100 mesh filter in-line on all flare fittings helps keep out particulate material and extend the life of the seats Contoured easy-grip handles for positive control; color coded for ready identification Sight glass to easily view refrigerant movement and condition during charging and recovery Heavy duty hook won't pull out