If you are trying to save a bit of money Ridge, you don't have to get the harness pack. I actually did not use it that much with Met. It should not interfere with the harness handle though if you fasten the pack using the forward rings on the harness. There is a velcro strap on each side of the harness pack that you loop through a ring on the harness. I can not get at Met's right now so can't recall if it also has velcro on the back of it or not. If it does not I think I put some as I seem to remember that. The only thing I did not like is that the girth strap was not padded. I changed that in a nanosecond as Met did not have much belly hair. I really like the design though as the way the underneath portion is designed it keeps the girth strap back further from their front leg pits which prevents breakdown in that area as well as allowing more easy free movement. I know Lee from when I was on a swim team for disabled people in California. She's a great lady. If you talk to her again- tell her I said hello. Karyn and Thane