j/fit Plyometric Box for Training & CrossFit – Available in 6 Inch, 12... $41.54 – $294.84 Make sure this fits by entering your model number. INDESTRUCTIBLE PLYO BOXES: Our plyo boxes are made from high quality materials so as to last for the many years to come. The heavy duty steel construction guarantees safe and dynamic performances. STABLE RUBBER STOPPERS: Excel your routines but keep your posture safe with our plyometric boxes. The rubber stoppers on the bottom are screwed for optimum safety and will keep boxes from sliding.