For riders who prefer a bit more style and a more powerful grip, the Thunder Riser Set is the right choice. The upper clamp features ribs just like an antique Chevy Small Block and has a cast Biltwell logo. Made of lost wax stainless steel, always with stainless steel screws. Lasts forever. Lower part with 1/2 "-13 threaded holes (screws not included), suitable for handlebars Ø: 1".