Call 800-555-3694 for pricing. Sold in full pallet quantities only. Tongue and Groove mean that each piece has a protruding tongue side and a receiving groove side. The Tongue and Groove each run the entire perimeter of the piece, all 4 sides. The purpose is to control vertical movement between adjoining boards. Horizontal movement is still allowed to a small degree and, in fact, is a desirable quality, since wood flooring will expand and contract.