Featuring High-Performance Heated -Diode Sensor Technology Detects refrigerant leaks as small as 0.4 oz/year Automatically self-calibrates to neutralize background contamination Sensitive to both R12 and R134a refrigerants. Certified to meet SAE J1627 High/low sensitivity switch for accurate diagnosis of both large and small leaks Low battery indicator guards against unreliable readings Variable-intensity audible alarm plus flashing LED help pinpoint leaks fast 17" chrome-plated flexible metal probe holds its position in tight quarters Easily replaceable foam filter protects sensor and pump Includes replacement filters, (2) D cell batteries and rugged carrying case