This self-latching top and bottom fire bolt is for use on a wood door. The self-latching top bolt latches when the inactive leaf closes and stays latched until it is retracted manually. The bolt automatically engages when the inactive door closes. When the active door is opened, the inactive door stays latched at the top until the top bolt is released by pressing the plunger button on the bolt face. Low (5 lbs. maximum) closing force. Override feature prevents damage to doors or bolt if bolt head is blocked from entering strike. Bolt head rod is adjustable up to 1-1/2". Thermal lock automatically locks the inactive door under high heat conditions due to fire. Bottom fire bolt eliminates need for floor prep. Oversize fire bolt strike hole allows for slight door misalignment. UL listed.