Indeed, thanks for starting this useful thread.
The hole in the end of the handlebars has an inside diameter of approximately 12 mm, which is slightly smaller than 1/2-inch.
My Tusk D-Flex Handguards are designed for holes at least 5/8-inch in diameter. Therefore, I tapped the 12 mm holes for a 1/2-inch coarse thread, and bolted the handguards to the ends of the handlebars.
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Spud
"Never argue with an idiot. He will drag you down to his level, and beat you with experience."
Mark Twain
2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
2005 Honda XR650L
2004 Honda CRF250X
1998 Kawasaki KDX220
Mods made to my Zongshen ZS200GY-2:
http://www.chinariders.net/showthread.php?t=6894