9/16" STEEL ZINC HEX NUT (7/32" THICK). 
The thickest of our steel locknuts. 
It is 9/16" outside diameter with 3/8" machine cut threaded hole. 
(works with 1/8 IPS pipe). 
7/32" thick. Heavy zinc-plated. 
$2 minimum charge orders less than $20. 
$.50 packing charge for each parts box.