Easily monitor your shipments for damaging cold temperatures with Labelmaster’s ColdMark™ Freeze Indicators. These show when your products have been exposed to cold temperatures for more than 30 minutes during transport. Simply peel the release liner off their back, and the pressure-sensitive adhesive quickly adheres to any dry surface inside or outside the packaging container. Their colorless bulb turns an irreversible violet color once the temperature falls below the indicator's response temperature. Save time and money bringing transportation damage claims to a quick resolution with these handy shipment indicator tools. These items must ship Next Day Air in thermal packaging to avoid activation during transport during cold months.