The KWA M33 AEG cylinders come in three different configurations, including types 1, 2, and 3. You can find the stock models with their types below:
Type 1: KM4A1, SR10, KM4 RIS, KM16 Battle Rifle, KM4 SR12, KR12, KR14.
Type 2: CQR Mod 1, KM4 Commando, KR9, SR7, CQR Mod 2, KM4 CQB, KR5.
Type 3: No current production model uses the KWA Type 3 cylinder, but it’s perfect as an upgrade for high speed builds where a higher rate of fire is desired. The centrally located port allows a faster piston return, speeding the cycling process.
*It should be noted that there are no true "universal" types of cylinders, and each manufacturer's ports will vary slightly. A Type Zero cyinder is a cylinder that has no port and thus has maximum compression, which is great for high power (FPS) builds, but will the rate of fire, because there is more compression for the piston to return to its rear position to prepare to fire the next BB.