From BiblePortal Wikipedia

Holman Bible Dictionary [1]

 Exodus 38:26Weights And Measures

Hastings' Dictionary of the Bible [2]

BEKA (AV [Note: Authorized Version.] Bekah ). See Weights and Measures.

International Standard Bible Encyclopedia [3]

bē´ka ( בּקע , beḳa‛ , "half"): Half a shekel, the amount contributed by each male of the Israelites for the use of the Sanctuary ( Exodus 38:26 ). Its value varied according to the standard used, but on the ordinary, or Phoenician, standard it would represent about 122 grams. See Weights And Measures .