The W6 is a wider XL version of the W5, which is a reclined seat with a reclined seating position suitable for very low profile cars such as the GT40. Seat belt harness holes are included. A five or six point harness is advised with any reclined seat. This is the black GRP version.
An alternative and popular covering option is a Dinamica® suede two-piece seat pad set which is a special-order item.