This is the Univerque "Curvb" (curvy curb) - a fingerboard curb with multiple, differently curved edges.

The base body is solid and is made of relief casting compound. Then the surface is treated with hard wax. This protects it and makes the curb very pleasant to ride without using additional lubricants.
With 1050 grams of weight, it is so heavy that it can not be accidentally moved. Nevertheless, additional foam rubber has been applied to the bottom to resist stronger collisions.
The curb is 180mm long and 100mm wide. The straight edge is at a height of about 42mm.

The relief casting compound has similar properties to very fine concrete. It is very hard and very fine pored.