I remember well, either my parent would not or could not buy them for me, so I saved my money. Little by little; I still remember walking into the toy store, the store I would often stare at this toy within the window display. How I wanted these so much! I was about 10 years old back in the 50s; my desire was to own these plastic bricks.
Believe it or not, I still have these blocks presently. The round box they came in is long gone but I found this image on the Internet today. Mine are also all white with longer red blocks (coping) to finish my creation/house. The coping blocks in my set are red not green as shown in the below image.
Yes, I still have most of them, however, my grandchildren will not play with them the way I would, they prefer the modern Legos.