Shellback, formerly known as eDivo, is a free mobile app developed by SeaWarrior Applications to support US Naval Surface Force (SURFOR) personnel. The app provides easy offline access to key SURFOR information, making it an essential tool for Sailors while underway without the need for an internet connection.

The app provides the most relevant and current information to SURFOR Sailors in one location and is scheduled for annual updates. The information is divided into several main categories, including Admin/Training, Medical, Operations, Personnel Management, Safety, and Rules of the Road. Each category contains multiple documents and manuals relevant to that category. For example, Admin/Training contains the Correspondence Manual and the SURFOR Training and Readiness Manual, while Medical includes the Manual of the Medical Department, information on medical and physical readiness, mental health, Medical Evaluation Board procedures, the Disability Evaluation System, family member readiness, and more.