That is a factory hardtop.It will fit all Spiders from 1970-1982.It may also fit Spiders from 1983-1995. The front of the hardtop attaches to the top of the windshield frame with two latches that are identical to the latches used on a convertible top. The rear of the hardtop is held in place with two turnbuckles.
Mine looks just like that. It's a Parish top, not OEM. I believe the OEM had side windows, and not a wrap around rear window.
Mine clips onto the front like the soft top, but does not attach to anything in the rear or sides.
Note- chrome around sides and front were removed for refinishing.