Auralex Cornerfill Cube Charcoal
CornerFill Cubes are a terrific way to finish out trihedral corners where three LENRD Bass Traps come together. Great for gyms and larger rooms.
Even without LENRDs, CornerFill Cubes offer excellent bass absorption and can look really cool, especially with other Auralex treatments butting up to them.
For both products suggested adhesive is 1 Foamtak or 1 Tubetak Pro.