This is the first LED watch made by the Bulova , it was launched in 1973. The official name is Bulova Accuquartz 228.
In watch is incorporated Hughes LED module which has been specially modified for Bulova, so If you have a defective Bulova Big Block you can easily repair it by replacing the module from any no name led watch who has the Hughes module, all you need to do is make small changes to the contacts on module (switch original metal contact with hole on center from Bulova module and put it on to Hughes, cut off settings contact because now there is a switch for time reading, then insert new module into the Bulova yellow plastic holder), of course, you need a little electronics skills and a soldering iron to do something like this.
This one Big Block I present to you is a total mint condition, all original, on the quartz crystal case you can see the date when it was manufactured, mine is from May 1976.
Unique and distinctive design, some say it is ugly, some that is beautiful but always leaves a strong impression. The last ones were manufactured in 1977.