HELP! question about rockwool slabs.

i was looking to purchase rockwool slabs, 8inch wide, 3ft long, 3inch tall. question is do i need to purchase the cubes as well, in order to transplant a smaller cube? help anyone?

It's best to start your clones is rookwool cubes. 2" sqaures are good ... they stand up & are deep enough for cuttings. Depending how long your clone stem is, you don't want it sticking out through the bottom of the cube. Cutting cubes from a slab is the most economical way. Once your clones root & acclimate set them in your flushed for 24 hour ph balanced slabs. Water them at least 3 times a day for 5 minutes. Don't ever let it get dry. Good luck