Back to the Future II was ahead of its time when it comes to 'hoverboards.'

The flying skateboard from the film didn't arrive in the real world in time for Back to the Future day Wednesday--October 21, 2015. But that hasn't prevented some electric skateboards from being referred to as "hoverboards." 

The trend started when rapper Wiz Khalifa was arrested at Los Angeles International Airport in August when he refused to get off his electric skateboard, which he called his "hoverboard." The motorized skateboards were illegal to ride in California until earlier this month when Governor Jerry Brown reversed a 1977 law banning them. The ban was intended for loud, gas-powered devices, and the new products whizzing around today are virtually silent and emission-free.

Here are three companies that have already rolled out innovative versions of the electric skateboard.

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First-time entrepreneurs Sanjay Dastoor, Matthew Tran, and John Ulmen founded San Francisco-based Boosted Boards in 2012 with backing from incubator program Y Combinator and startup accelerator StartX. All three co-founders are in their early 30s and hold graduate degrees in mechanical engineering from Stanford.

Boosted Boards makes an electric skateboard designed to simulate the feeling of snowboarding, surfing, and wakeboarding. The board has two modes--standard and expert--which allow the rider to control the speed and torque limit according to his or her preferred riding style. A Bluetooth remote controls acceleration and the brakes. 

Boosted Boards raised an undisclosed seed round in 2013, and has fewer than 50 employees. The company sells to customers in the U.S. and Canada, and is investigating bringing its light electric vehicle technology to other products. Boosted Boards' device weighs 15 pounds and has a top speed of 22 mph. Price: $999.

New York-based PhunkeeDuck was founded in 2015 by Matthew Waxman and Maxx Yellin, two entrepreneurs in their mid 20s who previously started iPhone accessory company PhunkeeTree in 2012. PhunkeeDuck's flagship product is a two-wheeled scooter that looks like a Segway without handles. The company has yet to raise outside capital, but plans on raising its first round and adding two additional versions of the device in the next six to 12 months, according to Waxman.

PhunkeeDuck has 15 full-time employees and about 30 brand ambassadors in the U.S. The company's flagship product weighs 18 pounds and has a top speed of 12 mph. Celebrities who have shared photos and videos of themselves using the device on social media include Khalifa, Justin Bieber, Nick Jonas, Kendall Jenner and Nicki Minaj. Price: $1,499.

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San Francisco-based ZBoard was founded in 2012 by Ben Forman and Geoff Larson, two first-time entrepreneurs in their late 20s. A member of incubator 500 Startups in 2013, ZBoard is currently backed by hardware incubator Highway1. The company has fewer than 15 employees and does not plan on raising VC money in the next year.  

ZBoard's first-edition electric skateboard has been available since 2012, and the founders recently raised $1 million in crowdfunded preorders for the ZBoard 2, which begins shipping later this year. The first version of the product comes in four different models, and each model's deck includes front and rear foot pads that riders step on to accelerate and brake. ZBoard's devices weigh between 25 and 33 pounds and have top speeds of 16 to 20 mph. Price: $599-$1,399.