boom base

Traditionally, a hunk of cast iron, weighing approximately fifty pounds and containing female threads for 1.5" pipe in the center.


http://mail.altmanltg.com/publicsynergy/docs/BLItemDossier.asp?Item=B-50&PLID=&Country=US

Newer designs allow for more convenient transport and storage:

http://www.ssrconline.com/pipes.pdf