Ambu Per t ACE is a one-piece design that adjusts to any adult/size neck with 16 different settings ranging from Neckless to Tall sizes. The Ambu Per t ACE incorporates latches that allow the rescuer to size the collar exactly to the victim's neck size. Two safety lock buttons hold the collar in place when adjusted. It folds completely ï¬‚ at and frees up valuable storage space. The collar is radiolucent, CT and MRI compatible.