Polar Thermal vaccine bags are designed to safely transport vaccines from A to B, however in circumstances where the bag will be opened and closed, vaccines taken out for use then we strongly recommend using the Coolants and/or Vaccine Safety Pack. The 3 litre utility bag is designed so that one layer of vaccines can be sandwiched between layers of PolarChill Gel Packs Once the bag has been used the coolants will need to be conditioned again – the recharge pack enables you to have a second full use whilst this process is completed – very useful if you plan to use the bags every day. For the 3 litre bags the pack consists of 4 x PolarChill Gel Packs.