These plugs are 100% in normal composting conditions, no industrial composting necessary, declared non-toxic. Ideal for any kind of automated system. Using seeds or cuttings can be continued in blocks or pyramid full cycle. The material is self regulating, less prome to error providing much more stable values like the air to water ratio, ph and EC levels with much success. The square plug is 3.5x3.5x3.0cm, Volume: 0.035L, Weight:26gr, Weight dried, 3gr, Air to water ratio:20-80, EC 1.0, ph 5.8