CORTEX Soft Plyo Box Modular Stackable 15cm, 30cm, 45cm, 60cmStack them high for the ultimate challenge in plyometric exercise. The Cortex Plyo Box Stacking Set with four boxes gets progressively taller, and combines to make a maximum of 150cm vertical. Part of a modular set, our Soft Plyo Boxes are designed to be used in combination to progress with you as you improve, or give you access to different exercises. To support stacking, the boxes have Velcro tabs that lock boxes in place to stabilise them through