There are other reasons the Shelter *might* justify the higher price. They may have taken a page out of Grado's book. It's my understanding that the whole Grado Prestige series is made on one production line. Grado then runs them through QA for frequency response, linearity, and trackability, and badges and prices them according to how well they perform. And they get a price range of $40 to $180 out of this "same" cartridge.
Plus, the difference in stylus dimensions indicates that the Shelter and Sumiko are not *exactly* the same.
Plus, the difference in stylus dimensions indicates that the Shelter and Sumiko are not *exactly* the same.

