I previously had GU10 bulbs in my house and decided to change these to GU10 LED bulbs whilst using an existing dimmer switch I purchased from Screwfix. Once these new GU10 LED bulbs were fitted I could hear a buzzing sound coming from the dimmer switch!! I contacted these guys who were very informative, knowledgeable and willing to help. I explained my situation and they suggested to purchase these trailing edge dimmer switches, once installed no buzzing could be heard and they operate fantastically!! Definitely recommended product and service! Thanks guys.