1/2 (12.7mm) diameter brass abandon plug. Thread size is pipe thread size.

Manuals & Documentation
Catalog Number 825A-1/2
Manufacturer Legrand-Wiremold
Brand Legrand-Wiremold
Country of Origin China
Made in USA No
RoHS URL http://www.ideadigitalcontent.com/files/11311/ROH_Legrand_ROHS_statement.pdf
UPC 786564264606
GTIN 00786564264606