You can count on the sun coming up tomorrow, but its performance might not be reliable after that. On clear days, the sun provides more than enough ultraviolet light to cure UV resins, but cloudy days are a different story. A tube of UV Wader Repar and a UV Nano Light are an excellent insurance policy against a day ruined by leaking waders. Small and durable, with a twist on/off to prevent unintentional battery drain while not in use, the UV Nano Light all but disappears in a vest or pack pocket, only to re-emerge when the day needs saving.