The wrist strap, made of
a textured rubberized plastic on my unit, can be replaced like a regular watch band: you could put a leather band on, or a DayGlo one, or find one in a watch store.
The side bezel is
plastic, with a
textured,
rubberized finish on the back that feels comfortable in - hand, and yet won't attract dust or particles as some
rubberized backs we've seen (though it does seem to scratch fairly easily).