^No purchase necessary. This promotion is available only to life science professionals 21 years or older in the US (excluding Puerto Rico) and Canada who plan to use the sample within 4 weeks of receipt. Sample requests must be received by December 31, 2017 or until sample supplies are depleted, whichever comes first. Limit one free sample per customer. Please allow 6 to 8 weeks for delivery. Cannot be combined with other discounts or promotions. Offer void where prohibited, licensed or restricted by federal, state, provincial, or local laws or regulation or agency/institutional policy. Other restrictions may apply.