WP40 is the perfect gender reveal smoke to celebrate the coming of your baby . This smoke grenade produces brilliantly coloured non-toxic smoke over approximately 90 seconds. The unit is discreetly packaged, so the sex will remain a secret until the pin is pulled. The Enola Gaye Wire Pull® WP40 is the world’s most popular smoke grenade. It’s simple to operate, just read the instructions and safety notices, then when you are prepared to go, pull the pin. The smoke is delivered from the single vent at the top of the grenade.