Construction: Investment-cast and CNC-machined stainless steel. 5/16" x 18 t.p.i. Stainless steel bar clamp hardware. Fitment: This one-piece riser fits rigid- and rubber-mounted top trees with 3.5" (89mm) center-to-center mounting holes only (Wide Glide, Narrow Glide, H-D aftermarket trees, etc.) If your top tree has different mounting holes, Thunder risers will not fit your motorcycle. Also, the holes on your trees must accept 1/2" O.D. hardware. The lower clamp is threaded to accept 1/2"-13" mounting hardware (not included). Details: A large number of late-model Harley owners who prefer tall handlebars convinced us to develop the Thunder risers. This riser one-piece design increases riser stiffness and clamping power on rubber-mounted top trees, and is a boon to performance and style on practically any motorcycle.
