Bests & Worsts Reviews from Amazon

Quick overview of notable features: WP-660= lightweight, LED panel, timer, massage setting. WP-100 Ultra= built solidly, better accessory holder (holds more/easy to reach), overall cleaner appearance (coils/wand go back neatly). WP-660c. "New model" • The new WP-660 is lighter (610 grams), but feels flimsy/cheap. •Case is very thin. • Clear water reservoir container, BUT you can't read the measurements when attached because they face/covered by the small accessory storage area. • Accessory storage holder only holds TWO tips (you receive 7 tips total/3 are the same). Inconviently placed on the inside. • Wand holder is much smaller and narrow. The coils are difficult to put back neatly due to this downgrade. This gives the unit an unkept appearance. • More compact, but it is taller and you lose the accessory tip holder. • Does have a stutter at 30 seconds and 1 minute. A nice feature. • Does have a "massage" mode. The other nice feature. • LED panel --------------------------//------------------------- WP-100 Ultra. "Older model" • The older WP-100(ultra) is heavier (1,100 grams), but feels much sturdier. • Blue colored water reservoir, but you can read the measurements. • Comes with 6 tips (only 2 regular tips instead of 3, otherwise the same as WP-660) • Accessory storage unit holds 4 tips. Located on top of reservoir for easy access. • Wand holder is wider and longer, but is very easy to use. The coils neatly go back without much (if any) effort. This makes the entire unit look clean and maintained. *Here is a link of a side by side comparison: http://waterflosserreviews.com/waterpik-ultra-vs-aquarius/