We designed The Heat Protector to drastically reduce the temperature of the drinking rim area ( the part of the bottle that touches your lips ) and the lid in the hottest saunas. It's created from the same Neoprene x Natural Cork composite material as the outer sleeve of The Sauna Bottle and simply fits onto your existing lid. Simply use the included Allen Key to unscrew the black carry handle, slide the heat protector over the lid, align the holes with the gaps and then screw the carry handle back on. It fits snugly over the drinking rim area - effectively insulating it from the intense heat of the sauna and keeping the rim area much cooler. If you use wood-fired stove saunas which operate at 85 degrees celsius + and tend to stay in the sauna for longer than 10 minutes at a time then this is a good fit for you ! If you use electric stove saunas only or saunas which operate at lower temperatures then you may not require this. This is an accessory for The Sauna Bottle.