Grub’s boots are 100 per cent waterproof, keeping feet warm and dry in the harshest of conditions. Their secret? A unique self-insulating waterproof Insu-foam Ultra shell that acts as a natural medium between inside and outside temperatures. Grub’s neoprene footwear comes in two ranges, the 5.0 and 8.5. Boots with 5.0 Technology are lined with moisture-wicking terry knit, which keeps the wearer dry and comfortable in a range of -10ºC to 30ºC. 8.5 Technology boots have a polyester fleece lining combined with a downy Highloft liner that wicks away excess perspiration and creates a comfortable temperature range of -40ºC to 15ºC.