Undercover Canopy Accessories Gravity Weight Tubes (4 Tubes, Four Straps, Black) 4 Tubes with attaching easy to use boat straps Adapts to all Types of free standing canopies and shelters Easy to fill each tube with Sand, Rock or Water, adds up to 180 lbs. of Leveraged weight to your shelter. Durable Heavy Duty PVC Construction, Satisfaction guaranteed. Easy to transport, just fill them at the site of your event. No need to carry the extra weight around with you all the time. 4 Tubes, Four Straps for anchoring Canopies and Gazebos