These head blocks are sold in pairs with the chin strap included. They are extremely durable and are the strongest in the industry. They will not break when the board is dropped, like other blocks in the industry. These are far superior to every other block, and one pair of blocks will last many seasons. You may pay a little more initially, but these will never need replacing and will save you a fortune in the long run. These are a great replacement when the blocks on your C.J. board breaks. These will only fit on the EG spineboard or the CJ spineboard.