Thanks tjk,
The problem with the commercial sites is that they typically show the gross weight of the package for postage, not the nett weight of the item itself. Also, they can be a little unreliable. One of them listed the Mighty Mouse at 6 pounds, LOL!! The 1.5 pounds for the keyboard cited by Vanns sounds about right, but other commercial sites offer slightly different numbers...
I am after the exact nett weight without packaging. This is why I have been looking for an official specifications sheet.
I am totally perplexed by the absence on the Apple website of an appropriate specifications sheet for these products.
I appreciate your advice — thanks for getting back to me.