Sizes: 7" x 11" O/D Size: 260mm x 362mm; I/D opening: 178mm x 280mm; Cut Out: 208mm x 310mm (8180089) 8" x 12" O/D Size: 318mm x 394mm; I/D opening: 210mm x 290mm; Cut Out: 273mm x 329mm (8180090) 10" x 20" O/D Size: 350mm x 597mm; I/D opening: 248mm x 496mm; Cut Out: 305mm x 535mm (8180086) 16" x 18" O/D Size: 463mm x 514mm; I/D opening: 359mm x 407mm; Cut Out: 413mm x 448mm (8180087)