"Module trays of my own design, made of recycled polypropylene which is strong and durable. The trays have wide holes at the bottom that enable plants to be pushed up easily and also improve drainage. The tapered cells require less compost and result in no waterlogging around the roots. The polypropylene creates smooth and solid cells that help plant rootballs slide upwards with little or no damage to the plant roots, and none to the tray." (Charles Dowding)