This model is a simple receiver box to allow you to insert a Halo UNSC A.I. Chip into the back of a Halo Master Chief helmet. This model is measured based on the dimensions of the following objects: Chip: Halo 4 Cortana Light-Up Keychain Helmet: 'Disguise'-branded Halo 5 'Master Chief' costume helmet, adult size This receiver box is inserted by carving out a rectangular hole into the back of the helmet and inserting the box into it, glueing into place. You can then add a Halo A.I. chip, that you can insert or remove - a perfect, subtle addition to your Halo SPARTAN cosplay that adds a touch of realism. The box has two hollows to allow you to glue 2 10mmx2mm neodymium magnets to the box. If you then carve out two corresponding hollows in the chip itself, using a rotary tool or Dremel, you can glue in two corresponding magnets and the chip will magnetically lock into place once inserted into the helmet. The length of the box inside the Disguise helmet does not interfere with the room inside the helmet - it does not touch the back of the head or bulge out the internal padding. There are two pilot holes to add decorative screws once finished, or you can leave them as-is. Disclaimer: The terms HALO, SPARTAN, Master Chief, Cortana or UNSC are all trademarks of the Microsoft Corporation - I do not claim ownership for any of these properties.