Here ya go.  I spent 6 years in Texas.  We had to have these. The cowboys would have rather died than take their boots off to comply with an ESD rule.  http://www.esdproduct.com/shopdisplayproducts_bertech.asp?id=38&cat=Heel+%26+Toe+Grounders  The model 7520 is the one you looking for.  

Kat