Traditional goggles use 12-15mm of face foam, establishing fit by tightening the goggle strap thus compressing the foam to fit the contours of your face.
Because the I/O MAG 3D Imprint is designed for your unique face shape, this allows for lower strap tension. If you are used to higher strap tension you might need to adjust your I/O MAG Imprint 3D to a looser fit to experience the full benefits.