1/4-20 x 1" Hex Head Machine Bolt. Used only in M12K Purple Martin House mounting bracket. Secures clamps to the top section of a 1-1/4" OD telescoping pole. Use #32019 1/4-20 Nylon Insert Locking Nut as a fastener. Also found in #900060 Mounting Bracket Assembly complete hardware pack. MINIMUM ORDER - 2