Check the listing for details. ULTRAponics GroTube 4" END CAP for replacement or DIY Hydroponic Systems.. Condition: New. Listed at 12.95 USD. Hello. Thanks for looking. This listing is for one ULTRAponics, Inc. END CAP as used as one of the proprietary parts for our ULTRAponics GroTube made of FDA-certified food grade plastic in the USA. This is a new part intended for use as a replacement for use at each end of the ULTRAponics GroTube or other 4" diameter tubing. Includes adjustable 4" metal O-Ring. If you're making your own hydroponic system based on the "Flood and Drip"/"Ebb and Flow" Method out of 4" PVC, these parts are for you. For each system you're making, you'll need one Plant Site, one Strainer, one Plate for EACH plant, plus one Fill, one drain, two End Caps and either two Elbows or two Tees for each GroTube in the SYSTEM. Plans are included with parts purchase. See also: our other proprietary parts, including PLANT SITE, PLATE, STRAINER, DRAIN, ELBOW, TEE and END CAPS for replacements or DIY hydroponic systems that you build. Order as many as needed. 1000s available. See our website for more information: www.ultraponics.net Will ship quantities and mixed/matched ULTRAponics parts at actual shipping cost and will also ship internationally for additional actual cost.Made in the USA !!!