Mark One, a San Francisco-based startup, has created a sensor-loaded bottle that can track your hydration. The goal is to help you stay healthy by combining data about how much you drink with your weight, height, and fitness.

A mobile app paired with the Internet connected bottle tells you how many ounces of liquid you take in during the day. It also nudges you to drink more when it determines that you’re not drinking enough.

The connected water bottle

Mark One’s Pryme, as it is called, resembles a travel mug with sensors discretely embedded in the sides. A thin vertical stripe on the bottle’s side lights up to display how hydrated you are. When the green dot at the top of it lights up green, you are at your hydrated best.

If that isn’t enough sci-fi for you, there’s this: The bottle comes with a plastic coaster that serves as its wireless charger. Yes, you must charge your water bottle like a mobile phone.

The sleek and modern design is quite pleasing to the eye, as far as bottles go. But it’s not the only such product out there. Thermos has a similar bottle, and several upstarts are also developing their own, like Trago, HydrateMe, and Ozmo.

Pryme connects to its companion iOS app, the Apple Health app, Apple Watch, and Jawbone UP fitness tracker. You then enter a few pieces of information about yourself like your height, weight, gender, age, and how active you are. Throughout the day, you can check the glowing line on the bottle or the mobile app to see your current level of hydration as compared to your optimal level. It also tells you how many more ounces of liquid you need to drink.

I got a Pryme to test out for the past week. I mostly only used it at the office because I tended to neglect it at home. The design of the bottle’s opening makes it a little awkward to drink from. That’s particularly true if you take it to the gym, where you risk spilling it while exercising on the elliptical machine. It also holds only 16 ounces of liquid, while my old-school water bottle holds 23.

Starting on Tuesday, customers can order Pryme through Mark One’s website and through the online Apple Store and a limited number of Apple’s retail stores. It comes in one color, white, retails for $99, and is currently only compatible with iOS.

What happened?

A year and a half ago, Mark One, the company behind Pryme, had promised a “smart cup” that could automatically identify the liquid inside and provide information like the amount of sugar and caffeine it contains, and how it impacts the user’s hydration level. Intrigued, thousands of customers pre-ordered the seemingly magical product, called the Vessyl, with the promise they’d receive it this year.

But Mark One didn’t deliver. In its place, the company introduced the Pryme, a far less ambitious product.

Like any hardware startup asking consumers to pre-order an unfinished product, there are risks. If anything, that’s what crowdfunding services Kickstarter and Indiegogo taught us—you might not get that gadget you ordered, ever. But still, it had raised money from big-name investors and attracted folks like high-profile tech designer Yves Behar, former Nike designer Jason Mayden, and former engineers from Apple and Microsoft’s Kinect division.

So what happened? Where’s the gadget we were promised?

Like many entrepreneurs find out, developing technology often takes longer than expected. Mark One hoped to have the product ready by early 2015, although it later pushed it to the fourth quarter. Now, not only has that deadline come and gone, but the company couldn’t even share a new target timeline when I spoke last week with Nic Barnes, the company’s head of brand and marketing.

Last year, when the company showed prototypes to journalists, the unit it used did indeed work. However, the sensors were still in development and the bottle had limitations. Technology for detecting a specific beverage (“this is 12 ounces of Diet Coke with 46 milligrams of caffeine”) was incomplete.

Since then, the company has gone through an executive upheaval. Justin Lee, Mark One’s co-founder, is no longer the startup’s CEO and now serves as a company advisor. Barnes said the company needed new leadership because of the product delays. It turned to Hamid Mohammadinia, who previously led the startup’s engineering team and formerly served as a manufacturing design lead at Apple (AAPL).

“He’s looking at what it’s going to take in order to close that reliability gap,” Barnes said of Mohammadinia’s challenge following the delay of the original Vessyl.

In addition to Lee, Jason Mayden, previously the company’s vice president of design, is also no longer at the company, but serves as an advisor. According to his LinkedIn profile, he’s currently a designer at Accel Partners and working on a new startup. Dr. Mark Berman, originally the company’s vice president of health, is now working on an different project, though Barnes declined to share more details.

On the slightly bright side, customers who pre-ordered the original Vessyl product will get a free Pryme water bottle to make up for the delays.

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