The extension nipples feature one-piece construction of solid brass. The outer dimension has been "diamond" knurled for ease of installation. They are available in 1/2 or 3/4 in IPS and several lengths. They have been designed to be used as sprinkler head extensions when a drop nipple length has been cut too short or when the finished ceiling has changed from its intended location. Using the appropriate length extension will allow for realignment of the sprinkler head without removing and recutting the drop nipple. This represents a significant cost savings to the sprinkler installation company. Check with local authority having jurisdiction prior to use.