Photographs courtesy of Casiophile
CASIO | W-550
RELEASED | UNKNOWN
The module 81 is the lowest numbered module to appear in any Marlin watch and this model is not listed in Casios PINDEX (1993). The heavy Stainless steel case is bulkier than the W-350 or W-450, in fact it's nearly as large as a DW-1000. The bracelet integrates cleanly into the case and the dial design is a nice, understated blue.
WATCHES WITH MODULE 81