Owing to the different subdial layouts of each watch, the hand-wound Sellita movement in each watch is different, though they are part of the same family of calibres. The Segrave uses the SW536 M MP, whilst the Cobb has the SW530 M MP a. Both movements offer identical features, incorporating a monopusher chronograph complication with a central chronograph elapsed seconds hand and 30-minute counter, operated by a pusher at two o’clock.
Both calibres are elaboré-grade, beat at 4Hz and have a 62-hour power reserve when fully wound. The only notable difference is in the jewel count. The SW530 in the Cobb has 25, and the SW536 in the Segrave has 29. The difference is because the SW536 incorporates an additional gear train to reposition the small seconds sub-dial.