Gaiam - Cork Yoga Block (100% Naturals & Reusable) Improve your yoga routine with the low-impact Cork Yoga Block. The all-natural cork block, which measures 9 by 4 by 6 inches (W x H x D), will help you refine your alignment and balance in certain standing and sitting poses. It's particularly effective in lyengar yoga, which employs props within its postures to improve strength, stamina, and flexibility.