1 inch Rockwool cuttings cubes. Available individually, in a tray of 77 or a box of 693 (9 x 77). They combine efficiency in terms of both crop growth and plant handling. SBS 1" rockwool blocks are supplied in a specially manufactured black tray which excludes light from the root zone. For more information on using rockwool read Integral Hydroponics for useful tips,or Hydroponically Speaking- Cloning.