If you're always looking for a cool supplement to enhance mental function, check this one out by Neurofuel. You can try one bottle for free with this rebate offer. All you need to do is click the "get sample" button, then enter your phone number to participate in the rebate offer. Purchase a bottle of Neurofuel at your local Sam's Club and send them your receipt. You'll receive your money back via Venmo/Paypal. Enjoy!