The Seiko Prospex SPB421 is a great watch for divers and watch enthusiasts. It can be used during underwater diving trips, outdoor adventures or daily wear. The watch has an approximate case thickness of 13.2mm, a case diameter of 40.5mm, and weighs 180.0g. It's easy to carry and suitable for people with different wrist sizes. Whether you're exploring the ocean or just going about your day, this watch is a reliable companion.