A cannon attachment is a device that is used to increase the accuracy and range of a cannon. The two most common types of cannon attachments are EER, which stands for Extended Range Envelope, and ADE, which stands for Advanced Design Envelope. EERs are designed to increase the range of a cannon by up to 30%, while ADEs are designed to increase the accuracy of a cannon by up to 20%. Both types of attachments are used to improve the performance of cannons in military and recreational settings.