Projector offset, presented as a percentage, refers to the distance between the center of the lens to the image bottom (when placing the projector on a table) or image top (when mounting the projecting on a ceiling). 

For example, when placed on a table, a projector with a 100 % offset would project an image whose bottom edge is in line with the center of the projector lens and that extends upwards. A 125% offset lens would project an image whose bottom edge is 25% of the image's height above the center of the projector lens.

Knowing the offset of a projector will help you decide how to position the device -- Whether to place it above the screen, below the screen, or mid-screen without tilting the projector.

The offset of all Nebula projectors is 100%; that is to say, when placed on a table, a Nebula projector would project an image with the bottom edge in line with the center of the projector lens and the remaining extending upwards. Thus, simply position your Nebula right towards the wall at a proper height without tilting it to have a great watching experience.