Symposium Acoustics is the best known maker of roller bearings, and their Rollerblock Series 2 and Rollerblock Jr. are fine products at a fair price, really well made. Before ordering either, consider the roller bearings offered by the Canadian company Ingress Engineering. They offer three models, the best (and most expensive of course, but still cheaper than both the Symposium models) of a decidedly better design and build than even the Rollerblock Series 2.
The bowl carved into the Ingress cup is of a larger diameter than that in the Symposiums, producing a lower resonant frequency (and therefore better isolation). The bowls are then polished to a mirror-like finish for lowest friction. Also, the cup is manufactured out of the harder 7075 formula aluminum, as opposed to the softer 6061 of the Symposiums and the cheaper Ingress’. Three cups with ball bearings for under $200, a good value imo. For those preferring a top and bottom cup, the bottom-level Ingress is of the dual-cup design. As good as the Symposium Rollerblock Jr., at about half it's price.
