Stud Parts are bolts used to lock certain B-Daman parts in place.
The Battle B-Daman version of the Stud Parts comprises of two halves which is the Nut and Bolt. The Nut has an (-) shape tip which fits in the Key-shaped Assembler Tool. They are usually found in accessories such as the DHB Unit and Wide Server.
Cross Fight B-Daman
The most prominent use of Stud Parts is seen with the Cross Fight B-Daman series wherein its use is mandatory as it holds the Body Parts and Core Part altogether. Each B-Daman from this series usually has four Stud Parts that hold everything together in place - one in each shoulder attaching the Arm Parts to the upper part of the core and two under the feet part. There is a sheer exception such as Force=Dragren in which a completed version would require a total of six Stud Parts in which two extra Studs are placed in the Gravity Arm.
Stud Parts are nearly always the same color as the Assembler Tool and/or Hold Parts as they usually come from the same runner. The only exception to this is Dravise. Also, Stud Parts are not only made with plastic, but also metal. The more-durable Metal Stud Parts can only be found in the Takara-Tomy Twin=Drazeros SP Set.
Each Starter Package or Core Random Booster usually comes with four to five Stud Parts in the same runner as the Assembler Tool and Hold Parts. There is also a different mold of Stud Parts for Cross Fight B-Daman and Cross Fight B-Daman eS.