Seiko 5 Sports Automatic Polyester SNZG15J1-var-NATO28 100M Men's Watch The five key characteristics of Seiko 5 receives a boost with its Sports designation; now far more durable, accurate and reliable than the usual Seiko 5. The outstanding legibility and a more robust case construction of this field watch hark back to the military-styled watches from the past. The polyester strap is extremely durable with a Union Jack pattern on it.