I have the EVO IAS model which has the cavity to hold an audible similar in shape and size to a Protrack. Installing the Protrack is routed from the inside of the helmet and visible from the right side. Removing the audible is also pretty easy to do. The cavity is rather secure and I don't have to worry about my audible falling out of the helmet. The EVO is quiet during freefall and I can easily hear my Protrack with no problems, even in the low volume setting. Overall it's a pretty comfortable helmet to wear. I also have the Z1 full face and the sizing for the EVO does run smaller. My Z1 is size large and I needed and extra large for the EVO. The strap serves its purpose well and helps keep the helmet snugly in place. Once you get accustomed to it, locking and unlocking the strap is not a problem and can easily be done even with gloves on. A rough riser slap once completely dislodged the Z1 (but later recovered)off my cranium although it was securely fastened. But I'm not as paranoid about losing my EVO since the fit is more secure thanks to the chin strap. I wear Kroops goggles or Nike sunglasses with my EVO. Both the goggles and sunglasses fit well with this helmet. If you're concerned about looking good on video, donning sunglasses with this helmet looks badass. I've also tried the Z1 Eyes goggles and the fit was noticeably tighter. I can't compare this to other open face helmets since this is the only one I've tried. I also can't comment on durability because I've only had it one summer. I've had good clean landings and no collisions so no comment on actual protection design either. Based on visual inspection, it looks solidly built and don't expect any problems. The liner is easily replaced and washable. A washable liner is a big plus if you sweat alot. The liners have one pouch in each ear if you're interested in using more than one audible.
