The greater trochanter is the bony bump on the outside of your upper thigh, right at the hip joint. It sticks out and takes the brunt of impact when you fall on your side, making it the most common site for hip fractures on the slopes.
Every ski hip protector should cover this area—it's the bare minimum for effective protection. When shopping, check that the padding sits directly over this bony prominence, not just on the soft tissue around it. A protector that's shifted or poorly positioned won't do much good in a fall.
If you're unsure about fit, look for products that specifically mention greater trochanter coverage, and try them on to feel for the pad placement over that outer hip bone. This core coverage is non-negotiable—any additional protection like tailbone or thigh padding is a bonus on top of this essential area.