3/4" diameter stainless steel needle. Quick shutoff valve. Recommended 5 lbs. of any soluble nitrate solution to 100 gal. of water. Push unit in ground as far as possible. Open valve partially to let water pressure aid in pushing unit to depth of 18" before completely opening valve. 250-300 lbs. of pressure is recommended. Subjet puts out 16 1/2 gallons per minute. 5 gallons (20 sec.) per hole on a 4 foot grid is recommended.