Duluth Trading Company, which developed Longtail T-Shirt — with an extra 3-inches in length in the back to fend off plumber’s butt — is opening its 25th brick-and-mortar store Sept. 7, 2017, in the Larkridge shopping center in Thornton. This is the interior of a store in Hoffman Estates, Ill. Coloradans searching for shirts to hide unseemly plumber’s butt, comfy underwear to last through a long workday, and sturdy outdoor clothing for camping, hiking and fishing should look no further. Duluth Trading Company, inventor of the “Longtail T-Shirt” — with 3 inches of extra length to defend tradesmen from accidentally revealing their backsides — is coming to Thornton. A longtime catalog retailer for working men and women, Duluth Trading is setting up its first Colorado store in the Larkridge shopping center at Interstate 25 and Colorado 7.