I have a pair of black Continental Giants (below) that I purchased on eBay a while ago. They aren't a completely matched pair as one is embossed with "Turnbull" and the other with "Hanimex". I bought them for sentimental reasons as I remember seeing them in a sports store here in North-East England back in the late 1950s after my parents had given me a Turnbull Sea-Raider green triangular dive mask as a birthday present.
They are great fins, powerful and virtually indestructible. I've used them to snorkel with in the North Sea, fitting them over the feet of a vintage drysuit to keep myself warm and dry. I wasn't aware that they were available in alternative colours such as blue and yellow. A collage below shows Continental Giants in a period advertisement and with their unique instep straps. It's hard to believe that these fins were first launched over sixty years ago! So sad too that they are no longer in production anywhere.