When the bolt is closed, this loader allows you to load the tube without having to worry about the stock loader pinching your fingers. It holds itself open to allow for dual and quad-loading like you'd find on a competition shotgun. If you don't think you need or want that functionality, you probably don't want this.
This is a video that *could* be used as a de-facto installation guide: https://www.youtube.com/watch?v=Kr5-9TeLRsY
And this showcases someone with the Pro Lifter installed ghost loading their 1301T: https://www.youtube.com/watch?v=8FWaJbxGI1g