Product review (5 stars): Buy in quantity
Nice to have replacement panels around when they are needed.  Have noticed that mold will begin to grow on the panels if they are left in too long.  Also tried rinsing these panels, yet the mineral buildup makes cleaning them difficult.  The panel is made with a lightweight metal, which allows the water to flow well and provide good humidity (their intent).  This is definitely a disposable product, so buying this 10 pack makes life easier when a replacement is needed.  Besides, the cost break makes these panels more affordable.