Exodus 25:17
And you shall make a mercy seat of pure gold: two cubits and a half shall be the length thereof, and a cubit and a half the breadth thereof.
Torrey's Topical Textbook—AKJV

Exodus 37:6
And he made the mercy seat of pure gold: two cubits and a half was the length thereof, and one cubit and a half the breadth thereof.
Torrey's Topical Textbook—AKJV