illustrated in fig3 a the upper wall 78 of the channel 74 is recessed into the lower surface 58 of the surrounding case 46 thereby permitting the band 14 to fit more closely against the wrist 30 of the wearer 106 6 in a further variant as illustrated in fig1 the watch module 34 includes an analog watch movement 110 7 in still a further variant as illustrated in fig4 the watch module 34 includes a digital watch movement 114 8 in yet a further variant the watch module 34 is waterproof 9 in a variant of the invention as illustrated in fig1 17 the attachment mechanism 50 further includes at least one first side wall 118 the first side wall 118 is attached at a right angle to the lower surface 58 of the surrounding case 46 and descends from it for a first predetermined distance 122 at least one underband plate 126 is provided the plate 126 is attached at a right angle at a proximate edge 130 to a lower edge 134 of the first side wall 118 the plate 126 has a width 138 at least equal to the first predetermined width 18 and is spaced from the lower surface 58 by at least the first predetermined thickness 22 at least one second side wall 142 is provided the second side wall 142 is attached at a right angle at a distal edge 146 of the underband plate.