Clamshell VentilatorStainless steel13520: 38.1mm x 41.3mm 13521: 54mm x 54mm13527: 130.2mm x 114.3mm x 54mm#100/CTN13528-S: Small, 171.5mm x 149mm x 60.3mm #50/CTN13528-L: Large, 193.7mm x 174.6mm x 70mm #50/CTN