Boyd’s Bible Dictionary:
(knobs). Globular ornaments on the capitals of pillars (2 Chron. 4:12-13). Called “bowls” (1 Kings 7:41).
Concise Bible Dictionary:
Anything round. It formed some part of the chapiters of the two pillars in the temple built by Solomon (2 Chron. 4:12-13). The same word is translated “bowls” in 1 Kings 7:41-42.