Bread-Bakers v110.n031.1

The recipe wants "vital wheat gluten", which is nearly pure gluten 
protein. You can get it from King Arthur and Bob's Red Mill, among 
others. To be sure you're getting the right thing, check the 
nutritional information:

KA vital wheat gluten: 7 grams of protein per 9 gram serving = 77%

KA organic high gluten flour (described as "14% protein"): 4 g 
protein per 30 g serving = 13.3%

Jeff