This brush appeared on my bar the other day. It took a day to find out who put it there! My sister sent it to me by way of my son, and he has no idea why, She is not answering her phone. I am assuming that she knew we could tell her what it is for!
Maker is Loew-Cornell, a company known for artist supplies and such. Their online catalog has plenty of brushes, but not this one.
Marked Loew-Cornell , #91 Taiwan.
It is 6" OAL, the wooden moveable piece is 1 1/4" long with a diameter of 7/8", the brush is 1 1/2" long, and the pointed pin is 1 5/8" long.
I'm guessing that the pin is for cleaning the brush.