--a) Metal parts may corrode depending on their storage conditions. There is a risk of the corroded parts staining the product, so products should be kept at low humidity, avoiding hermetically sealed storage in plastic bags or cardboard boxes and allowing some breathability in storage. (Please also be aware of the effects of NOX.)
--b) The use of cleaning products containing fluorine, or contact with fabric on which such cleaning products have been used, causes metal parts to become discolored. Please be cautious of this.