Check the extra long bolster pillow's warranty - There should be a warranty provided against flattening. But, you need to remember that a warranty can affect a pillow's price.
Money-back guarantee - A pillow's manufacturer should offer a guarantee on a product's quality to ensure your complete satisfaction.
Quality - You would want a high-quality bolster to support your body weight and last a long time as well. Most high-quality pillows are handmade or hand sewn, but they're usually expensive.
Your special needs - There are bolster pillows that are tailored to meet the specific requirements of users. For example, there are people who require specialty pillows for their allergies. The best pillow for you if you have an allergy is one that's filled and covered with materials that are capable of keeping away mites and dust. If you snore, choose a bolster that will ensure your airway is not compressed while you sleep.