This kit will make a total of 4 mecha heads so you can customize your kits. Each head is made from a Main Unit, Face Unit, Side Units, and a Visor Unit. These parts can be combined into over 200 combinations of head units. Multiple types of neck joints are included for compatibility with most Frame Arms armor. Users are free to choose the length of the joint. This product is not compatible with some products such as Kagutsuchi. The model consists of three colors: light gray, dark gray, and clear. The set included ball joint for a neck is 5mm wide, which makes it compatible with the 5mm ball joint for HEXA GEAR kits. Package contents: Head Unit A ×1, Head Unit B ×1, Head Unit C ×1, Head Unit D ×1, Neck Joint A ×2, Neck Joint B ×2, Neck Joint C ×1, and Neck Joint D ×1.