As @JB said I think the only difference is the sapphire back and front rather than hesalite and solid case back.
Correct. And anyone with a brain knows the only way to buy a Speedmaster Professional is with hesalite.
@JB started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
As @JB said I think the only difference is the sapphire back and front rather than hesalite and solid case back.