Where does my Mattress Protector go? August 11, 2020 20:08 The Helix Mattress Protector fits snugly around your mattress, under your fitted sheet. Related articles Can I buy the Mattress Protector without buying a Helix Mattress? Can I wash my Helix Mattress Protector? How are the GlacioTex Waterproof Mattress Protector and GlacioTex Cooling Cover different? What does the Mattress Protector do? Will the mattress protector make me sleep hotter?