Material:

Upper: 66% polyester, 34% polyurethane
Outsole: 100% rubber, 4 mm
Removable insoles
No animal materials

What we love about these shoes:

Waterproof barefoot shoe
Wide toe box - provides ample space for toes
Zero drop - allows for a natural foot position
Easy to put on and take off thanks to elastic Velcro straps

Fit:

Length: Generously long
Width: Fits narrow to normal-width feet, perceived as a fairly narrow model.
Volume: Fits low to normal-high feet - can also accommodate a higher instep due to adjustable lacing

Regularly treat the shoes with a protective spray to shield them from dirt while maintaining the waterproof membrane. For example, this one from Collonil.
TIP: For more of a barefoot feeling, you can wear the shoes without the insole, which also adds a bit more width to the shoes.