The Blue Grade is the most widely used thermal vest for use under wet suits. It provides warmth over the entire back and has a usage time of up to 4 hours. New to the family is the Blue Grade Plus. The heating element is divided into two parts. The heating part is fixed on the upper back. The second part of the heating element is incorporated in a cummerbund. This cummerbund gives you the freedom to place the heating element on the back or on the belly. Purely according to the needs of the user himself. The Blue Grade Plus is, just like the Blue Grade, equipped with two 2.2 Ah batteries of the type C. The control goes through the CPS (magnetic) switch which is guaranteed to be watertight up to a depth of 50 metres. Of course, the Blue Grade Plus can also be used in a dry suit. The Blue Grade and Blue Grade Plus are standard stock items and available in sizes XS to XXL.