This is the Bard Singlet by Rufskin.
Its replacing my (now 8-years-old and falling apart) Nasty Pig singlet that I usually wear.
They’re nearly identical. Same material, similar cut, except the Bard Singlet has an asymmetrical mesh swish that contours your midsection. This helps accentuate your curves (and rump) better than the Nasty Pig version. Highly recommended.
Buy it here.