Krystal 8" Dual-Speed Inline Extraction FanKrystal 8" Dual Speed Inline Extraction Fan A well priced 8" (200mm) inline fan with two speed settings, suited to medium to large tents (1. 5m+) where a 6" just can't shift enough air. The dual speed switch lets you ramp up for peak flowering with a filter in line, or drop down for quieter veg stage running. Why growers choose the Krystal 8" Dual Speed: Two speed settings full power for flowering with a carbon filter, lower speed for veg or quieter