Complex sentence: A safelight usually consists of an ordinary lightbulb in a housing with a coloured filter, but it is possible to buy special bulbs and fluorescent tubes which are coated with a filter directly on the glass.
Split into simpler sentences: A safelight usually consists of an ordinary lightbulb in a housing with a coloured filter. It is possible to buy special bulbs and fluorescent tubes which are coated with a filter directly on the glass.