The product is a paperback book titled "Concord 1039 ZSU-23-4 Shilka and Soviet Air Defense Gun Vehicles" by Steven J. Zaloga. Published in 1992 by Concord Publications Company, the book focuses on the ZSU-23-4 Shilka and other Soviet air defense gun vehicles. Written by military historian Steven Zaloga, the book provides detailed information and analysis on these specialized military vehicles, making it a valuable resource for enthusiasts and researchers interested in Soviet military technology.