Waterproof board / Rebar ua haujlwm trolley yog cov txheej txheem tseem ceeb hauv kev ua haujlwm hauv qhov av. Tam sim no, phau ntawv ua haujlwm nrog cov rooj zaum yooj yim yog feem ntau siv, nrog cov tshuab qis thiab ntau qhov tsis zoo.