Wow, that is some spider!  :) 

hewalker, Thanks  for the info. I'm glad you included he photo, it  answers my other concenrs quite well.

Thanks, missed that and the width range, 1 1/8-2". I wonder if the fingers can be adjusted sideways, can fit over doubled strings and be set up for 3 or 5 courses.

According to the web site the spider capo mini should work on mountain dulcimers.  “The Mini SpiderCapo is for narrow necked instruments. These include, but are not limited to: Banjo, Ukelele, Mandolin and Bouzuki.

Users report that because the SpiderCapo clamps over the fingerboard, and not behind, it can also be used on the Mountian Dulcimer.”

I looked at their site earlier today to see if they published any specs. I couldn't find any. I I wanted to find out what the open width is [ 1 3/8 to 1 5/8"], if the fingers are sideways adjustable so they can be placed over different string spacings and if they work on flat fingerboards [I don't use any of the instruments they make them for]. They also offer custom made. If they will work oh MD's , there could be a lot of unique tunings done.

I had never heard of the spider capo, so after looking it up, it is quite similar, but probably better, than one called "The Extra Hand Capo."  I had (and still have) one of those and it was really cool experimenting with the different strings held down with open strings.  Even tho' I don't like capos (they cut off too many frets) I might have to try one of those.