Yes I have heard of it. It is made by a company called Vet A Mix. It is most common to the tablets called Pet-Cal which more people are probably familiar with.
Here is my opinion on this (without knowing how old your dog is and guessing it is still a pup since you are getting the ears done).
Feeding additional calcium and/or providing calcium supplements will only increase the daily calcium intake, since your dog food should already contain calcium. This would make calcium intake above the levels shown to increase the risk for developmental bone disease issues later in life. Because virtually all dog foods contain more calcium than is needed to meet the requirement, the use of a calcium supplement certainly is unnecessary. Calcium supplements are generally given to older dogs to aid in bone loss, to dogs with bad teeth to help correct tooth and gum problems, to dogs after they have a broken bone or fracture. They seldom are needed in what is considered a large breed rapid growing puppy.
I am not sure if the person who suggested it to you was your vet. If it was then I guess they have experience with it that I have not seen. I stopped doing ears about a year ago and maybe something new has come out. If it was not your vet then I would give the vet who will be doing the ears a call and ask them if they suggest it. Adding ear growth (forming of cartilage) also causes more blood flow to the ear and it is hard doing an ear trim when they are bleeding more then normal.
My personal opinion is that you dont need it. A great ear crop will stand!