Mnpctech 360 (3x120mm) grills fit radiators and measure 14.5" x 5-1/8" wide with 15mm spacing.
*All Mnpctech 120mm, 240mm, 360mm, 480mm, radiator grills have 15mm spacing for the fasteners.
Here is radiator grill fastener spacing for each PC radiator manufacturer.
16mm: Alphacool, Phobya, Magicool, Coolgate, EK, Swiftech
20mm: Hardware Labs series, Koolance