Plug Inserts 72 Cells Seedling Trays are joined cells in a flexible plastic sheet for inserting into No-Hole flats (ZHG115). These flats break apart into 12 sections of 6 cells each, or can be kept intact, depending on your garden needs. This size is great for planting individual seeds like lettuce or tomatoes, or for small groups, like 3 onion seeds in each, before transplanting outdoors. 72 cells @ 3.75 x 3.75cm (1.5 x 1.5″). Please note that due to the wide and brittle nature of this product, we do not ship individual flats. Both the “B” and “C” sizes of this product come in a box that is 27cm wide, 8cm tall, and 53cm long.