HSM² Radial Face Insert Putter

The HSM² Radial Face Insert Putter carries the second generation of Bobby Grace's HSM insert system. Per bobbygraceputters.com, as reported by the publication, development on this update began after 2009, and the HSM² is described as an improvement over the original HSM, said to allow early roll in addition to the distance correction the first insert was built around. None of that comes verified, it's the maker's own account of the change, and it should be read as such.

What the record does confirm, through the maker's current product pages, is that HSM² inserts remain part of the lineup today, sold separately as Large Mid Firm and Large Tour Firm Radial Face inserts, and as a Small Blade Mid Firm version fit to a run of blade heads: Shiloh, Ollie, Switch Hitter Blade, Pro SS, 18 Blade, Crossbow, and Centercut. The F-18 Smart Fit model is built around this same interchangeability, with a faceplate that accepts either the Tour Firm Black HSM² or the softer Mid Firm Grey option, alongside an aluminum radial face for players wanting a harder feel. The maker's page for that faceplate lays out the logic plainly: "The two screws behind the face removes the plate and can interchange to a harder or softer face depending on your golf ball choice and green speeds."

Within the HSM line, then, the HSM² sits as the insert generation that outlasted its debut, still being sold and fitted into current Bobby Grace heads years on, with the Tour Firm and Mid Firm split giving players a way to tune feel and roll characteristics to their own conditions.