From a quick glance, you may think golf lessons and mattress sales have nothing in common. No one would blame you if you thought that, but there is actually quite a bit in common between the two.
Both are limited by strict parameters. With golf clubs, there will always be different sizes such as putters, drivers, etc. The same can be said with twin, full, queen, and king mattress sizes. Golf lessons and mattress sales also include products made from relatively simple materials, such as wood, metal, leather, and rubber. One other similarity between the two is innovation and improvement for both have been subtle and incremental.
Manufacturers in these industries are constantly pursuing innovation and differentiation, and the changes made are quickly copied or improved on.