There are two types with slight differences. The type you have were available for general retail sale, say Dri-Fit and L/R on the sock and are c. 65% cotton content. The other type are Player Exclusive (last sold at the '12 US Open), have no writing on them and are c. 75% cotton content. I have about 20 pairs left of the latter, bought at $2.99 per pair. Both are very similar though, and are the best tennis socks I've worn. Thorlos are too slippery and Elites don't breathe well.
As goes the 3 pack for $15 Half cushion Nike socks, they are my second favorite. Good cushioning and breathability.
As a heavy sweater and fast mover, quality socks and shoes are essential for me to stay in good health.