Made for the Post-2015 Primo Oval Large, this hinge and handle kit will not fit a pre-2015 Large. Primo changed the design at that point and the hardware does not cross over, so check the era of your grill first and buy on that basis.
What you get is the assembly that joins the dome to the base and lets it move: the hinge, the two bands that clamp the ceramic, and the handle. On a Large this hardware is worked constantly, since the Large is the size most people use as an everyday grill rather than a weekend one, and every cook is another set of open-and-close cycles through the same joint.
Replace it when the dome stops behaving. A lid that slams, sags, or rests unevenly against the base is telling you the hardware has lost its tension, and an uneven close is the start of a sealing problem as much as a mechanical one. Changing hinge, bands and handle in one go leaves the whole assembly the same age.
The grill it fits is the Primo Oval Large ceramic charcoal grill, including the Primo Oval Large All-In-One package. Since the sealing rims are exposed while the bands are off, the Primo replacement gasket for the Oval X-Large 400 and Large 300 is worth ordering alongside it. More parts for this grill are in Primo grill accessories.