This varies on the item sold on the site and the country it is sold to.

Dmx testers have a limited guarantee as they are a new item that rarely goes wrong unless tampered with.

Repaired lights often come with a 30 day guarantee though that does not cover mirrors or bulbs being broken or perishing or for international sales (though we will try to be helpful supplying parts etc).
This does not apply for knocked down prices on items.