These 1801 deep inserts coupled with our web flats or 1020 trays, offer you a quick and easy way to carry cell packs and pots to and from your field, greenhouse or growing area. Vacuum inserts made of polystyrene sheet material. This product contains 18 individual cells per sheet measuring 3″ deep per cell. Offers a quick and easy way to carry cell packs and pots to and from your field, greenhouse or growing area. Vacuum inserts made of polystyrene sheet material.