I have no frame of reference comparing this radio with a Jwin JX M-14 since
I do not own one.

As far as size, the seller's info page
http://www.its-a.com/ebayradio/K-939.htm
gives the following dimensions: Size 4 3/8" wide by 2 5/8' tall by 1 1/8"
thick, but I think it's actually a little bit smaller than that. It's
noticeably smaller than my DE1102.

I would measure it, but I loaned my new radio to a friend to see what he
thinks. He will probably order one as well.

My friend likened the radio appearance and feel to a very small
point-and-shoot digital camera (maybe an Canon Elph, he suggested), and I
can see the resemblance. In fact, he thinks it would be fun to hand to a
tourist and say "could you take my picture" just to see how they reacted.