Carriage bolt diameter is measured on the outside of the threads.

Carriage bolt diameter

Diameter and Thread count

Matching Products

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Prod. # Description Buy
3492
Flat washers, Silicon bronze, 5/16"
General use flat washer
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$0.66 / ea
$10.08 / 25
$92.70 / 250
3501
Lock washers, Silicon bronze, 5/16"
Split lock washers place tension against a nut after tightening, to help prevent loosening.
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$0.32 / ea
$4.82 / 25
$44.10 / 250