Yale EF-DC Easy Fit Alarm Door/Window Contact, White, DIY Friendly, Accessory for SR & EF Alarms, Suitable for Main Access Points

Perfect

As it says on box. Easy to fit and use

handy extra sensor for other doors/windows

Added to my existing smart alarm nice price easy to install

Easy to install and add to the alarm system, instructions good. No problems since installation.

This thing makes my alarm go off when the door is opened. That was why I bought it.

Works great ! Easy to link with system and fit. Great add on to the Yale smart home sr 330

Did not work waste of money

Really simple to install - especially if replacing a faulty one as the back part which is screwed into the wall can stay in place. I always find these devices quite expensive for what you get, but they do the job well.

Door/ window alarm sensor