The size tag has been cutout, but I'm guessing it's a 6 or 8.

Use the measurements as a guide. 

Excellent condition with minimal wear.

Key features

• Luon fabric is sweat-wicking and four-way stretch
• added LYCRA® fibre moves with you and stays in great shape
• this technical fabric is sweat-wicking, four-way stretch and breathable
• practice the power of choice wear this tank with your favourite bra to get the perfect support
• racerback straps give you full freedom to move
• long length helps this tank stay put and is great for layering
• imported

Fit + function

• designed for: yoga, run, gym everything!
• fabric(s): 
  Luon®
• fit: tight
• shelf bra: no
• support: none
• coverage: medium
• length: hip