If the starter plugs dont appear to fit in the trays then simply flip the tray over. The mesh side can easily hold the entire sheet of starter plugs, mini block strips or even individual gro blocks.
No matter which side you decide to use, the strategically placed tray legs raise your grodan rockwool above the trays water line, while allowing roots to grow and expand freely. Being properly elevated is necessary for producing healthy new clones. EVen though seeds and cuttings love humid environment, they hate to be wet on the bottom. Purchase your gro smart trays now.