This ED1 is slightly larger than the Vari-Flo ED14, with thicker materials of construction which make it the preferred valve for use with larger gnawing animals such as rabbits, chinchillas, parrots. All brass construction. THis valve has a barbed inlet connection (3/16") permitting hook up to Edstrom flex tubing. Due to water trapped at the end of the stem, the animal has no problem locating water, and when he drinks he moves the stem causing more water to flow. He regulates the flow of water by the pressure he applies. He will regulate the flow to just the required amount as he drinks, little spill. One nipple drinker will serve 5 birds.