STP1-11 is an automatic watch movement from Swiss Technology Production produced since 2008, with volume production beginning in 2012. It is a replacement for the popular ETA 2824-2 and uses the same wheel architecture. STP uses a longer, thinner mainspring, boosting power reserve to 44 hours. It also includes an extra jewel on the barrel arbor.
STP may have used an ebauche from Sea-Gull in China to build the STP1-11 family. Photos on the company web site previously included the label, “ST2100”, which is the identifier found on the Sea-Gull ST2130 movement. The same has been said of the Valanvron VAL-24. Due to their Swiss content and finishing, STP can legally classify these movements as “Swiss Made”, and the company may now construct most or all of the movement in-house.
Cal. STP1-11M is a hand-winding version measuring just 3.70 mm thick. Cal. STP3-13 is a related movement with a swan neck regulator.
The movement can be manually wound with the crown in position 1. Rotate the crown clockwise to wind the mainspring.
The date wheel is advanced with the crown in second position (one notch out). Turn the crown counter-clockwise to advance the date wheel by one day.
The time is set with the crown in third position (pulled all the way out). Rotate the crown clockwise to advance the minute and hour hands and counter-clockwise to turn them backward.