With the rise of refrigerant theft and huffing related deaths, it is now code to protect your air conditioning unit's refrigerant. The American made SHIELD Refrigerant Locking Cap does just that by saving homeowners money and helping avoid liability issues by shielding them from theft, tampering, leaking and huffing related injuries. The SHIELD's durable, all brass design paired with color coded, water-proof caps makes it the best locking cap in the industry.