TankTechsRx 26834 TankDrx for Plugged Black Tanks 16oz Clear RV toilet clogs and tank blockages Detailed directions inside label include web address to access video instruction Label includes instructions to build effective tool for clearing blockage - even works on 5th wheels All natural probiotic formula - NO formaldehyde - Made in USA Remove RV sewer tank clogs, clear sensors, eliminate foul odor