Cross reference
Exodus 39:35
35 the ark of the testimony with its poles, the mercy seat,
Exodus 25:17
17 You shall make a mercy seat of pure gold. Two and a half cubits shall be its length, and a cubit and a half its breadth.
Hebrews 9:5
5 and above it cherubim of glory overshadowing the mercy seat, of which things we can't now speak in detail.
Hebrews 9:8
8 The Holy Spirit is indicating this, that the way into the Holy Place wasn't yet revealed while the first tabernacle was still standing;