Hot Packs for Tube Warmer from Drager.  Accessory for Drager Accuro.  This item requires no electrical power supply and allows Drager Tubes to be used even when temperatures are below the limit stated in the instructions for use.  This ensures that measurements are accurate.  
The hot packs for tubes are cost-effective as the tube warmers can be used several hundred times and are easy to use. 

This pack contains 1 piece.