The Philips Respironics DreamWear is a simple strap with Velcro on each side but is vital to tightening the mask to prevent leakage and to get a good seal.
The headgear is only one size but has special antigrip material on the inside to prevent the headgear from riding up the back of your head so it is important that is it put on the right way up. The logo on the strap is the best indication of the correct way it should be.
*Image of mask for reference only
This is the replacement headgear frame for the DreamWear Gel Pillows Mask and DreamWear Nasal Pillow Mask.
Philips Dreamwear Guide