To do the Arch position, the receiver gets into a partial bridge position with their shoulders resting on the bed while their partner enters from a kneeling position. The Arch is often overlooked because of its perceived simplicity, but thanks to the fantastic penetration angle this sex position offers, it should be a regular part of everyone's routine. That being said, you'll want to make sure to use a pillow under the receiver's head to reduce the strain and risk of injury to their neck.