Small/Medium - The award-winning pressurized Geigerrig Hydration System allows you to spray water to hydrate, share, clean, cool, etc.--anything you need. The pressurization enables convenient in-line plug-and-play filtration for on-the-go access to natural fresh water sources. When you are done, simply flip your Hydration Engine inside out and place it on the top shelf of the dishwasher for easy cleaning and drying. The RIG Cadence is a lightweight, low-profile vest that can be used for anything your heart desires. Plenty of convenient storage for your phone, keys, and treats. (Fit image demonstrates - 5'2" / 110 lbs)
Don't forget to buy a filter. This reservoir is filter-ready. Also, you may want to consider buying a bulb holder if you are retrofitting to another pack -- not required, but nice to have.