How is Bait Vest utilized?

I am really curious about what Bait Vest is capable of doing. Extending optimal depth for all fish species seems like a really undirect and maybe unnecessary boost. I think it has to be utilized with some lures or fish species. But I don’t get what it will allow you to do after you utilize it. If anyone here uses the item or has knowledge about it can you explain it to me? I am trying to get a fishing set and I wanted to get off the beaten track. Thanks.