Ask any medical professional and they'll tell you, "protect two things, the head and the spine." POC makes more than one product that can protect your spine and complement their headgear, so you have choices. The Spine Ergo Flow Back Protector is minimal in design, yet it offers maximal spine protection. And that is its sole purpose.The Spine Ergo Flow is designed to be worn like a backpack. It's most comfortable when worn over a base layer and under a jersey. This way, you won't get any chafing and when you do hit the deck, the edges can't get caught on rocks as you slide and tumble down the hill. Remember, a pad that stays put, protects. You'll be armored by a segmented, injection molded polyproplylene shell. It's lined with sculpted EPP foam to minimize the impact transmitted through the hard shell. A spine-centered strip of mesh allows air to move through perforated vents in the outer shell. The webbing shoulder straps and wide, flexible elastic waistband work together to keep the POC Spine protector snug and in-place when you need it. It comes with snap-on cervical and coccyx protection to have an ultimate level of safety for days on the hill that you know might just get ugly.The POC Spine Ergo Flow Back Protector is White and is available in three sizes -- X-Small/Small, Medium, and Large/X-Large.