with fins or blades having different shapes, thicknesses or spacing

Full Title

Protecting lighting devices from thermal damage; Cooling or heating arrangements specially adapted for lighting devices or systems (lighting fixtures combined with outlets for air-treatment systems F24F13/078) > Cooling arrangements (air-treatment systems dissipating or using the heat of lighting fixtures F24F3/056) > characterised by passive heat-dissipating elements, e.g. heat-sinks > with fins or blades > with fins or blades having different shapes, thicknesses or spacing