Hoptroff makes hyper-accurate wristwatches, using both mechatronic quartz (1 second per year accuracy) and atomic (1 second per millennium accuracy) movements. Hoptroff has announced that on 30 June at 23:59:59 GMT, their watches will be the first to correctly insert a leap second at the correct moment.
For the vast majority of mechanical wristwatches, getting to the level of accuracy where a leap second matters is not realistic. A finely tuned chronometer movement may only be accurate to -4/+6 seconds per day. But for Hoptroff watches, accuracy to that leap second is important — via HODINKEE