Constant Latching Flush Bolt Model No. : FB510M - For metal doors FB510W - For wood doors   • Non - handed. • Label : A ( 3 - Hour Fire Exit Hardware ) • Face Plate : FB510M - 1" x 6-3/4" FB510W - 1" x 8-1/2" • Finish : US3, US4, US26, US26D, US32, US32D     • Used at top of door only, an automatic flush bolt should be combined for use at bottom of door. Or a constant latching flush bolt combines with the auxiliary fire latch, providing significant reduction in door prep and eliminating floor prep entirely. • When inactive door closes, flush bolt is automatically latched. Automatic Flush Bolts Model No. : FB610M - For Metal Doors Model No. : FB610W - For Wood Doors • Non - handed. • Label : A ( 3 - Hour Fire Exit Hardware ) • Face Plate : FB610M - 1" x 6-3/4" FB610W - 1" x 8-1/2" • Finish : US3, US4, US26, US26D, US32, US32D     • Use on inactive leaf of double wood/hollow metal doors. • Used in pairs at top and bottom of inactive door. If use one unit for top side only, it has to combine with an auxiliary fire latch which replaces the bottom bolt. • Full automatic, when active door is opened, inactive door is free. • Automatically locks inactive door under high fire/heat conditions. • Patented products : Taiwan Patent No.: 192118 China Patent No.: 512293 Japan Patent No.: 393327 USA Patent No.: Pending