GreenLock S12 Retainer Blocks: Volmoed have the sole production and distribution rights for the GreenLock S12 Retaining Wall Block product in the Southern Cape/Garden Route, see https://greenlock.co.za/ for more information. GreenLock S12 Retaining Wall Block is an easy and practical solution to erosion and soil retention. Also works great in the garden. 380(L) x 320(W) x 220(H). 12 per m2.