ClipClok is the same shape and size as iPod nano. ClipClok also has a working rear spring clip, just like nano. ClipClok fits into any and all iPod nano compatible watch kits. ClipClok is also waterproof, has a premium Japanese quartz analog watch movement with a date calendar and a 5 year battery. I designed these iPod nano watch accessories, and am currently raising funds for their manufacture on Kickstarter: http://www.kickstarter.com/projects/simonkwan/podkit-watch-clipclok-ipod-nano-case-watch-module