The Pebble Time, the smartwatch startup’s third-generation device, has raised $12 million in preorders on Kickstarter since its debut last week. Get ready to watch that number tick up higher.

On Tuesday at Mobile World Congress, Pebble CEO Eric Migicovsky announced a new version of Pebble Time, the Pebble Time Steel. Like the previous Pebble Steel, the Time Steel is a higher-end version of the smartwatch, and it’s available for preorder for $250. 

See also: Meet The New Pebble Time—Though Getting One Will Take … Time

The 40,000 people who preordered the Pebble Time for $159 or $179 can upgrade and keep their May delivery date. Migicovsky teased that the audience at Wearable World Congress, where Migicovsky will sit with me for an on-stage conversation on May 19, will likely be wearing Pebble Times if they got their preorders in.

The Pebble Time will support both old and new apps.

Wrist-To-Wrist With Apple

It’s in Pebble’s best interest to lock in those orders, because the Apple Watch is coming in April. Migicovsky has an answer for that. Pebble already lets developers build apps for its smartwatches. Now it’s going to let others build hardware for Pebbles, too.

What kind of accessory can you put on a smartwatch? Well, Pebble already sells straps. For the Pebble Time and Time Steel, you can now build what Migicovsky calls a “smartstrap.”

The smartstraps attach to the Pebble’s charging port, exchanging both data and power, which Migicovsky says is a first. One kind of smartstrap could be a battery that extends a Pebble’s working life. Another smartstrap type might be a heart-rate sensor that draws power from the Pebble’s battery instead. A GPS sensor could turn a Pebble smartwatch into a fitness tracker that can monitor runs without tethering to a phone—something the Apple Watch won’t be able to do at launch.

See Also: Hear From Pebble’s Eric Migicovsky At Wearable World Congress

“When you start adding sensors, it makes the [device] bigger,” Migicovsky told me. “You don’t need that GPS all day, you only need it for particular situations.”

Migicovsky argues that it will be far easier to create a smartstrap than a standalone device or an all-in-one smartwatch with more built-in features: “The sensor doesn’t need a battery, doesn’t need a charger, doesn’t need a microcontroller.”

Smartstraps will be easy to hack on, he promises.

“We’ll have a few things you have to sign,” Migicovsky said. “If you’re a hacker and want to create hardware that works with it, go for it. I bet someone’s going to make an Arduino smart strap.”

Smartstraps could turn Pebble Time smartwatches into GPS sportwatches, fitness trackers, or anything else hardware manufacturers can dream up.

A Wired-In Platform

In the past, Migicovsky has talked about Pebble’s smartwatches acting as a hub for other connected devices, bypassing smartphones. But that vision relied on the very newest Bluetooth technology, which isn’t seeing widespread adoption in the marketplace yet.

Migicovsky said Pebble “hasn’t set a date yet” for Bluetooth connectivity, but “it’s on the roadmap.” For now, smartstraps are the way to build on Pebble hardware.

Pebble is also taking care of the 26,000 developers it has signed up to build apps for its watches. The Pebble Time will run older apps, for those who don’t care to update for the Time’s new color screen. And in June or July, Pebble plans to release a software update for its older watches that will let them run the same software as the Time. 

“We can’t say we’ll support the old hardware forever,” said Migicovsky. But the company is trying very hard to treat developers well. “That’s all that really matters: developers and users,” he said.

It will be interesting to see how many preorders Pebble draws for the Pebble Time Steel. It’s now $1.3 million short of the current record for a Kickstarter campaign. And it will also be crucial to see how swiftly developers and hardware makers create new apps and smartstraps.

If Pebble succeeds in competing with Apple, it won’t be by building something sleeker or more powerful. It will win by being more open.

Pebble CEO Eric Migicovsky is speaking at Wearable World Congress on May 19. Order your tickets now and get $100 off the early-bird price by using the code READWRITE

Product and promo images courtesy of Pebble; all other photos by Owen Thomas for ReadWrite