Does anyone know anything about the ST1901K? It's a variant of the ST1901 that is supposed to be thinner. I can't find much information, never mind where to buy one. It's also called the TY2901SK. See listing here:
https://reference.grail-watch.com/family/sea-gull-st19-family/
https://reference.grail-watch.com/family/sea-gull-st19-family/