4 Pack, Poultry Watering Nipple, Screw In Watering Nipples Allow You To Create A Custom Sanitary Watering System With PVC Pipe Or Plastic Containers & Feature A 360 Degree Stainless Steel Nipple Tip, Nipples Are Screwed Into Pipe Or Plastic Container By Drilling A 21/64" Hole In The Bottom Of The Pipe Or Container & Inserted Using Pipe Thread Tape To Make The Connection Water Tight.