-Premium HDPE material is durable and crack-resistant-Each plate can be filled with 5.2 Gal sand-Fill the umbrella base easily with spouts-Equipped with hidden handle for easy movement-Each plates can be stacked up to save space-Circulation holes add friction and stability-Ideal for various places with convenient storage and transport design-Holes for inserting locking pins facilitate tight connectionâ- Weather-proof Material - Constructed of all HDPE material the square umbrella base is resistant to various weather conditions to support long lifespan. Besides the premium material is rugged enough to endure strong impact.â- Detachable and Stackable Plates - The four 20 "x 20" plates come with holes for you to insert locking pins (not included). Therefore you can lock the four plates tightly to obtain a perfect cantilever umbrella base. When not in use they could be stacked for space-saving storage.â- Easy to Fill Spout - - Built-in spout makes it easy to fill or empty the heavy umbr