Tokyo Marui, widely considered the gold-standard in airsoft, has built an empire on producing some of the highest performance replica airsoft guns on the market. They're also credited with setting standards for parts compatibility between many different manufacturers by setting strict manufacturing tolerances and specifications for other brands to use. Japanese made Tokyo Marui products are typically all high quality polymer construction. While extremely durable to Japanese airsoft standards and using 134a gas propellant, use of Green Gas in the American market will cause increased wear and tear on the slide and blowback parts. It's highly recommended to use 134a gas with this product or consider upgrading to TM-compatible metal blowback parts and/or slide assembly for this frame.
*Note: FPS measurements are for 134a gas propellant, not Green Gas. Use of Green Gas in a Tokyo Marui with a polymer slide will cause increased wear and tear. Damage to the slide or blowback parts due to use of non 134a gas is not covered under warranty.