Sand shifts when you lift it. That's the whole idea. Every rep makes your core and grip work to keep the bag steady. FORZA sandbags use a heavy-duty shell with reinforced stitching. They hold up to drops and drags, and their multiple handles let you shoulder the bag, bear hug it, or press it overhead. Strongman athletes use them for carries, HYROX competitors use them for lunges, and CrossFitters use them as a dumbbell swap.