Blue Strong & Flexible Polished: Dark blue, richly colored nylon plastic with a smooth finish.
About this Product
A Reuleaux Triangle of revolution with constant width 3cm. Hollow with internal stiffeners. Now sold separately so you can get a set dyed in different colors.
For the same material, the price on these is proportional to the surface area plus a constant. This tells you that although they all have the same diameter, the surface areas (and volumes) of these pieces differ. I believe this model has the largest surface area.