USB Humidifier Sponge Sticks Replacement

Each sponge stick is 4.5 cm long and 1.2 cm in diameter, weighing less than 2 grams, and manufactured from durable open-cell polyurethane foam. Intended solely for small USB-powered humidifiers and ultrasonic mist makers, they act as the primary water-wicking interface between the reservoir and transducer. Their cylindrical geometry ensures full contact with the ultrasonic plate edge while allowing free passage of vapour. The sponge’s graded porosity filters suspended solids without restricting flow—maintaining consistent mist density and reducing audible ‘gurgling’ caused by uneven water feed. Supplied in multipacks to accommodate seasonal usage patterns, especially during UK winter months when indoor relative humidity often drops below 30% RH.