Ideal where in-ground anchoring devices are not appropriate. Tank-style anchor has a 4-3/8"W x 3-1/4"H opening designed to fit over any round or flat rear crossbar. Hard plastic shell will not crack when filled in the field with 50 lbs. of concrete, 39 lbs. of sand or 24 lbs. of water. Large carry handle and stackable design allow for convenient storage. Overall size 8-1/2" x 8-1/2". Comes in bright yellow for visibility and safety. Please check the ASTM counterweight requirements for your specific goal when ordering to ensure proper anchoring.