Fountain Pen Desk Set order (4)

This vintage fountain pen desk set is in excellent condition. It has never been used and is still in its original box. The felt on the holder says AIMS on the back. I believe the holder is made of metal and parts are chrome plated. It is stamped Newton New Haven. I believe the horse is onyx, but I can't be sure. The pen says R.Esterbrook & Co. No. 1550 order. The pen and holder together, weight about 3/4 lb. I am guessing at its age. It belonged to my 105 year old aunt.