Exodus 26:19-21

26:19 and you are to make forty silver bases to go under the twenty frames – two bases under the first frame for its two projections, and likewise two bases under the next frame for its two projections; 26:20 and for the second side of the tabernacle, the north side, twenty frames, 26:21 and their forty silver bases, two bases under the first frame, and two bases under the next frame.