I have used these elbow guards a few times and I always forget they are on! I have hit a few trees with them and I don't feel anything! I have the S/M, I am a tall female 6'0 with super skinny arms and they feel lose at first but have the straps that help to tighten the guard and at the same time slip right under my long sleeve jersey. They are super lightweight and durable. My boyfriend has TLD guards and recommends his, but states that mine "look really cool and is a bit jealous"!