Crazy Colour Cation UV is a vibrant neon yellow shade that glows under blacklight. For best results apply to pre-lightened hair. 100ml bottle.This semi permanent dye will gradually fade and wash out in over 2-6 weeks, colours may vary depending on hair type and base colour, but feel free to email us for more info and advice! Please note that for hygiene reasons we cannot accept returns on this item except in the unlikely event of a manufacturing fault.