The fitness tracking company Fitbit has filed to go public. The company plans to raise $100 million, a figure that will shift as they pitch the company to investors and gauge demand. The company said it earned $336 million in the first quarter of this year, with income of $48 million. If that continues it would be on pace to roughly double its 2014 sales and profit.

The company also revealed details of just how many units it has sold. In 2012 it sold 1.3 million devices. Last year that number had grown to 10.4 million. The biggest challenge will be continuing that growth as tech titans like Apple and Google move into the space with smartwatches that promise to double as fitness trackers. The company quotes figures from IDC estimating that the market for wearable devices will reach 114.0 million units shipped in 2018, representing a $33.7 billion worldwide revenue opportunity.

Fitbit also reported strong growth in its "paid active users", growing from 600,000 in 2012 to 9.5 million in the first quarter of 2015. Fitbit Premium offers benchmark analytics, a digital trainer, and other perks for a price of $49.99 a year. With this side of the business, Fitbit is seeking to offer a full spectrum health and fitness product. It makes a much more aggressive projection on this front, writing that "based on information from industry sources, we estimate this market represents an over $200 billion opportunity and includes consumer spend on health and fitness services, such as gym and health club memberships, commercial weight management services, and consumer health products, such as weight management products and dietary supplements."

The company plans to trade under the ticker symbol "FIT." It's success is a strong contrast to Nike's exit from the fitness wearable market and the reported struggles of its rival, Jawbone. "Every time I look at our data they have a larger and larger share of our digital fitness market," said Ben Arnold, an industry analyst and executive director at the NPD Group. "For the most recent 12 months through March they have 74 percent of that fitness tracker market. A year ago it was 62 percent. They are growing their share in a growing market."