The volume pedal Casio VP-1 has a knob at its front to set the minimum volume. The pedal case is made from thick sheet metal covered with black rubber. Because at least latex based rubber sorts tend to dissolve easily when treated wrongly, I recommend to store the pedal in a quite airtight PE or PP foil plastic bag to prevent cracking from ozone in the room air. Also keep it away from any normal fats or oils (e.g. in shoe dirt or leather shoe polish, or phthalate infested smeary soft PVC) because they may dissolve it. If the mechanism needs lubrication, only use thick silicone oil (e.g. sold as latex care product in sexshops), because silicone is the only oil that doesn't destroy latex based rubber.