With these StepRisers you can quickly and easily increase the working height of the GRS MicroBlocks. Provided as a set of 5 risers, each one adds 0.5" (12.7 mm) to the working height of the GRS MicroBlocks. Reduce fatigue and increase efficiency, especially under a microscope. Designed for easy and secure stacking, the bases of the 2 MicroBlock models fit the molded pocket in each riser, or the riser itself can be used as the base. Made in USA.