Googling really doesn't reveal anything at all about Alexis or Impextra Corp.

The movement is a Seiko 3302A although you'll be hard pressed to see any identifying markings other than those of the retailer. It runs at 21,600 BPH and is similar to the later Seiko EL-370. Access to theses movements is through the acrylic crystal; the stem is removed by pressing a small tab between the dial and case edge; there is a battery hatch on the back.

All have a crown between 2 and 3! They probably date from about 1973.