NIKE Pro Dri-FIT 3.0 Arm Sleeves, White (Adult L/XL)

How do I find out my size?

Any way to get those symbols off before wearing? Don't like advertisements on my clothes

Is small/medium the right size for my son who's 6' tall but very skinny? Does the S/M size relate to the width or length?

Can this be use for high school volleyball