Lee's new Self-Start Siphon feature has made aquarium maintenance a whole lot easier! With the Gravel Vacuum cylinder submerged in the water, simply move it up and down a few times to activate the Self-Start Siphon. Designed to separate and remove debris from aquarium gravel. Stretch from 9 to 17. One Stretch Gravel Vacuum Cleaner Complete With Two 9 Cylinders, Self-Start Cap Assembly And A 72 Long Hose.: Size: 9-17 in.