A particularly soft, delicate and supple top-grain leather typically from a young sheep or goat.
It is very porous and delicate so be certain to apply a suitable protector before wearing and after each clean, avoiding wax based treatments so as not to clog pores and spoil the finish. For cleaning regularly, use a soft dry cloth or if dampened allow leather to air-dry naturally away from direct heat.
The cork footbeds come with a light coating of sealant to prevent them from drying out. When the cork no longer looks shiny apply a thin coat of cork sealant to prolong their life. For regular cleaning wipe with a dampened cloth or soft bristle brush. Allow to air-dry away from direct heat. Wearing these on most days will retain a lot of moisture so remove regularly for airing.
Birkenstocks are designed to be roomy this is needed to perform the natural rolling motion of the foot without restrictions - just as if you were barefoot.
Your toes and heel should not touch the rim of your shoes while standing in them. Most people are fine with a regular fitting, but if your foot moves side to side when you walk and adjusting any straps does not help, a narrow fitting may be more suitable.