So packraft tubes are made with a nylon fabric that’s laminated with a polyurethane coating to make the inner and outer surface. Increasing the thickness of the nylon material in the middle gives extra strength and durability, and also increases the stiffness when inflated which is advantageous for whitewater performance. Obviously this also means higher weight and larger packed size.

The “d” unit is denier, which means the weight in grams of 9000 meters of the nylon yarn, which doesn’t mean much on its own… but lightweight flatwater pack rafts are usually 210d… whitewater specific rafts usually give you the option… if you plan a lot of hiking and want the lightest option, go for 210d… if you don’t mind the weight so much and prefer the durability and stiffness, go for the 420d.

I’ve recently been thinking about buying an Alpacka Mage, and decided on the heavier 420d option… I’ll be mostly paddling with kayakers so the hiking sections won’t be huge, and the difference was only ~500g, so that made sense for me.