Natural pinewood, set of 3 with Small, Medium, Large. 

Dimensions
S: 28 (L) x 20 (W) x 12 (H) cm 
M: 33 (L) x 25 (W) x 14 (H) cm
L: 38 (L) x 30 (W) x 16 (H) cm

Can be fit comfortably into the Wooden Crate Jumbo.

Color of wood may differ slightly from images, due to lighting and general nature of natural wood material.