✓Six of each size so you do not have to work out which one your car takes before you order. Honda and Acura use both an 18 mm and a 20 mm washer across the same model names, and which one is on your car depends on the gearbox and the drivetrain rather than the badge. With both in the box the right seal is already in your hand when the plug comes out and the fluid starts draining.
✓Where each size sits, and why the lists overlap. The 20 mm washer 94109-20000 seals the transmission drain plug on front wheel drive cars — on a 2022 Civic with the CVT it sits in the AT transmission case group of the parts diagram — and moves to the rear differential on all wheel drive cars, where a 2022 Pilot AWD shows the same number in the rear differential group. The 18 mm 90471-PX4-000 is the transmission pan washer.
✓Neither size goes on the engine. The engine oil drain plug on Honda and Acura takes the 14 mm washer, Honda number 94109-14000, and that is a separate AUTOMAJOR listing. If you are under the car for an oil change rather than a fluid service on the gearbox or the rear axle, this is not the pack you want and neither size will seat on the plug. Search the number 94109-14000 and you will land on the right one.
✓The 18 mm is Honda 90471-PX4-000, catalogued as drain plug washer and transmission pan washer, crossing to 16955, measuring 18.2 mm inner by 25.8 mm outer by 1.9 mm thick. The 20 mm is Honda 94109-20000, which supersedes 90413-551-000, measuring 20.2 mm inner by 27 mm outer by 2 mm thick. Both are soft aluminum and both are single use rather than something to clean up and refit.
✓Covers the transmission and rear axle drain points across Accord, Civic, CR-V, Odyssey, Pilot, Ridgeline, HR-V, Passport, Insight, Element, Fit, S2000, Prelude, Crosstour, CR-Z, Clarity, Del Sol and CRX, and the Acura range alongside them. That list is for the gearbox and the differential, not for the engine sump. Suited to ATF DW-1, CVT fluid HCF-2, manual gear oil and Dual Pump Fluid II.