210mm x 70mm, 5mm thick (total thickness is 10mm: 5mm of abrasive bonded to 5mm glass plate).
Shapton GlassStones are very fast cutting and long-lasting. The ceramic abrasive is permanently bonded to a glass plate so the whole unit is very flat and very strong. The abrasive is extremely consistent and dense so you have a great feel and can produce very precise and clean edges, plus these have the convenience of splash-and-go sharpening (do not soak these stones).
The Shapton stone holder (sold separately) is designed to fit these stones perfectly and is quite heavy and tall, providing a great workstation. The more affordable Naniwa universal/adjustable stone holder also works fine for these stones.