12prs of 10.5mm super-quality wheelsets for 16.5mm track, each live axle to one wheel and pre-fitted with our pickup springs. Superb free-running wheel profile slightly better than RP25-88. Super fine tolerances in manufacture of -0, +0.002".. Including for squareness on the axles (Which is why we pack them so well - you cannot ship fine-scale wheels in a bag without risking quality). Gauge preset to the optimum running with this wheel profile - Please do not adjust unless absolutely necessary for your specific trackwork. Also included in each pack are a few more pickup springs and fine black wire for connections. (If you do not need them, remove springs by simply pulling firmly on the spring tab).