On Fri, 28 Apr 2006 18:16:20 +0100, "Dave Plowman (News)"
wrote:

I'm willing to bet they don't carry BSW.

Doesn't matter 1/4-20 is exactly the same as 1/4 Whit, to an accuracy
that's better than the likely manufacturing accuracy.

I use 1/4-20 for tripod thread inserts because I can buy them from
Canada (Lee Valley) more easily than I can be bothered to cut them with
a tap and die.