Weber part #9930 - one grate.
Measures 11-3/4 x 17-1/4. The diameter of the rod is 3/8". One stainless steel welded-rod cooking grate. You need to buy two to make a complete set. Grate weighs 9 pounds and is constructed of individual rods of stainless steel that have been robot welded together to withstand years of everyday grilling.

Also known as 7639. PE CI version is part # 7638.
The hinged version of this grate is weber Part # 98745

Fits the following Weber models--Genesis Silver B and C, Genesis Gold B and C, Genesis Platinum B and C, Summit 425, 450, 475, 625, 650, 675, Genesis 1000, 1500, 2000, and 3000.
9930 is also known as 97290.

Please visit Weber's parts lookup site to verify that you order the correct parts for the specific model and production year of your grill. Parts can appear to be identical but not fit certain year models. It is best to look up by serial number. The link will also help you find the alpha-numeric serial number.