RedRock Starter Block PRO, 4" x 4" x 2.5" (Case of 216)RedRock Starter Block PRO, 4" x 4" x 2. 5" (Case of 216) 42 40 Hole 10x10x6. 5cm 4 Inch x 4 Inch x 2. 5 Inch Commercial grade stone wool pro starter blocks sourced and manufactured in North America. Our Stone wool starter blocks are made in the USA and processed in Canada Wetting agent ensures nutrients are immediately plant available The high fiber density of the stone wool starter blocks makes better use of water and fertilizers while allowing dry