Just what it says: 25% off (almost) every item.
Note that 25% is taken off RRP, so you'll only get the better of the two discounts. You'll also lose the free shipping option if you use it.
There are better sales on Bellroy, Orbitkey, Fjallraven, etc. if willing to wait for them, but 25% off isn't bad if you're willing to dig around and compare prices.
can not join be a mamber