This is Tie Shell - The Colour Changing Tie. 

David Penn has created a gimmick that provides the perfect solution to the colour changing tie plot. 

The Tie Shell gimmick means that you can easily customise two ties of your own choice. This gives you the freedom to promote the corporate client's brand colours, create surprise or use the final revelation to underpin mentalism style routines. 

A short moment of misdirection is all that is needed to effect the colour change. 

The change at the end of the trailer occurs in real time! No Cuts or Edits!