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'Singles' magazine released some more eye candy for fans of Jessica and Krystal in the form of behind-the-scenes photos from the sisters' pictorial.

These pictures show the girls engagement in the shoot as well as their diligence as they strike different poses and facial expressions like the pros that they are.  Then, they are able to wind down a bit when the cameras aren't focused on them for the shoot. 

Check out these lovely sisters below.