New 4 pcs Air Bubble Disk Stone Aerator Aquarium Pond Pump Hydroponics 5" 5 " Air Disk: 5 "D x 0.6 "H Material: Mineral stone, 4 pieces of air stone disk 4 pcs Air Bubble Disk Stone Aerator Aquarium Pond Pump Hydroponics 5" Delivery time: By Airmail: Generally, delivery to USA takes about 10-35 days. Delivery to Canada,AU, UK, and other European countries takes about 14-28 days.