Suitable for use on half hour and one hour timber based fire doors when fitted in conjunction with a fire tested latch or lockplease note all m marcus products are designed to be fitted on wooden doors only and cannot be fitted to upvc structures10 year mechanism warrantyproducts with sprung sets will be replaced if within 10 years from purchase the mechanism breaks due to faulty workmanship or materials the warranty applies only to the original purchaser and is deemed void if breakage o