Bottle holders for shoulder strap.

These are the same water bottle holders I make for my custom packs with one small difference. I replaced the webbing loop with Velcro so they can fit different size straps.
If fitting to a pack that's not mine you would still need to have a 19/20mm daisy chain on the shoulder straps to attach the top clip too. The clip may fit 25mm webbing but it's not ideal. 
The pocket is made to fit the 750ml bike bottle size.
If you want one for an existing other brand pack that great, but I'm not going to modify or alter them for your pack so don't ask and it's your responsibility to check it'll fit before buying.
Price is for one.