Seiko 7006-8020, 21 Jewel Automatic from October 1971, a cushion case design a very ergonomic and comfortable watch to wear. The 7006 automatic movement, quickset date, sweep second, 43 hour power reserve, diashock system. 
One of the many cool things about Vintage Seiko watches is they are easy to date, check the first two numbers on the serial number, the one first one is the year, as below equals 1971, the second one is the month, 1-9 equal the actual months, then O, N, D equal October, November and December so it is October 1971, you must know what decade the watch was made, but that comes with experience.
Seiko Landmaster, Seiko A628 LCD, Seiko HiBeat Chronometer, Seiko 7006-8020, Seiko Sea horse 6601-9990, Seiko Sea horse 6602-8990, Seiko 6106-5470 Blue, Seiko 6106-5470 Gold, Seiko 6119-5460
If you are unsure how to date your watch you can use the Seiko year calculator. But you will still need to know the decade, a quick Google, or post a question on a forum, should quickly ascertain the appropriate decade. Or you can ask me, and I will be happy to answer!
