An attachment system of a wearable electronic device includes a removable module. The removable module includes a locking mechanism comprising a first portion having a substantially planar top surface and second portion that comprises a substantially non-planar bottom surface. The first portion and the second portion are coupled together. The locking mechanism also includes a first spring mechanism coupled between the first portion and the second portion. The first spring mechanism causes the first portion to be biased away from the second portion. The locking mechanism also includes a second spring mechanism. The second spring mechanism causes the substantially planar top surface of the first portion to be biased substantially flush with respect to the removable module and also causes the substantially non-planar bottom surface of the second portion to be biased proud with respect to the removable module.