Snap's back with Spectacles, round two.

Designed for use exclusively with Snapchat, the $150 Spectacles are sunglasses with a camera. They record circular video you can view in Snapchat.

How do they work?

With a single button on the glasses frame. Press it once to snap a 10-second video, or take a 30-second clip if you press it again. To take a still photo, just press and hold. When the glasses are recording, LEDs around the camera light up.

The glasses can store up to 150 videos or 3,000 photos at a time.

Once you've recorded footage, Spectacles pair with your phone via Bluetooth, then use Wi-Fi to transfer HD clips to Snapchat.

Spectacles come with a carrying case that also doubles as a charger. You'll get around 70 videos from a single charge.

How are they different from the first Spectacles?

Apart from some cosmetic tweaks like new colors, you'll find most of the changes on the inside. Here are the main differences to the original Spectacles:

• Weight: Snap miniaturized the electronics, so the temple is one-third smaller.
  
• Price: They cost $20 more than the first version.
  
• They now take still photos.
  
• Dual microphones: Snap claims they reduce wind noise and balance out audio from conversations.
  
• Field of view: It's now 105-degrees compared to 115-degrees from the first version, which means you'll get slightly less in your shot but fisheye distortion should be reduced.
  
• Water resistant: While taking them deep-sea snorkeling is out of the question, they can withstand splashes and shallow water. Snap doesn't provide an official water-resistance rating though.
  
• Prescription or polarized lenses can be swapped in when you order through Lensabl, and single vision lenses start at $125.
  
• Faster transfer times: Snap claims a video now takes 3 seconds on average to transfer to your phone compared to 9 seconds with the first Spectacles.
  
• HD video transfer: All videos are now transferred to Snapchat in HD.
  

When can I get them?

Right now at spectacles.com if you live in the US, Canada, UK or France. Unlike the first Spectacles, the new version is available immediately from the website. You won't be able to buy it from Snapchat's Snapbot vending machines.

Other countries will be able to order Spectacles from the website starting May 3.

Do I have to use them with Snapchat?

Yes. Because Spectacles record circular video, you can rotate your phone around to see more of the image when viewing clips in Snapchat.

Once you've got your clips, you can export single videos or stories from Snapchat to your phone's photo library, if you want to post them to Facebook or Instagram, for example. The catch? You'll see a white border around the footage because it's circular video.