Overview Reviews Product Description HSS General purpose BA (British Association) is a metric thread system devised by the British for small screws used in components with a thread form of 47 ½° Used for threading studs, bolts and rods that require external threads Clarkson Osborn Catalog Product Videos Custom Field Size #4 - 0.66 BA Outer diameter 13/16" Package quantity/sold as each 1 Product Reviews Write a Review Write a Review × Clarkson-Osborn #4 - 0.66 BA x 13/16" HSS Round Die TA44004 Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Review Subject * Comments *