The Model 4 was Seth Thomas's only known key-wind model, and it's very surprising that a key-wind watch would follow the stem-wound Model 1, but it was one of the four new models designed under Charles Higginbotham's tenure at the company. Only a few thousand were made and could be used in either open-face or hunting configuration, depending on the style of case.
The total production of the Model 4 was a little over 13,000 pieces in 23 separate runs, starting at SN 35,001 and ending at 718,200, giving it the widest range of the lower five models. The Model 4 was designated as Grade 11, and all were gilt with 7 jewels. The only known option was a key guard, which appeared around the third SN block.
The earliest known publication for the Model 4 is 1888, which also follows the departure of the Model 1. There are adverts for it as late as 1896, but production of the Model 4 apparently continued throughout the Old Eagle Series span and into the serial number range of the New Eagle line, which began at SN 700,000.
Small quantities of Models 2, 3, and 6 have been reported with keyed arbors, and it's not known if those are transitional pieces that can still be stem-wound or if they are key-wind only.
If they are stem-wound they would contain the standard winding parts like the arbor, yoke, crown wheel and idlers, but although technically able to be wound with a key, any of these oddball examples would still be classed by model according to their serial numbers and found on the SN charts on those particular pages .