Brass material: The adapter is made of high-quality brass with good wear resistance, ensuring durability and airtightness of the connection, suitable for long-term use. Easy installation: This cylinder thread conversion adapter requires alignment of the threaded connection before hand-tightening. Use a wrench to moderately tighten, avoiding excessive force to prevent damage to the sealing ring. After tightening, slowly open the gas source and check for leaks to confirm proper function. Working pressure range: Designed for use with working pressures up to 3000 psi (207 bar), well above the typical 100-120 psi required by home soda machines, allowing safe and stable inflation under controlled high-pressure conditions. Thread size: 1 x TR21-4 female to TR21-3 male thread conversion adapter. Provides compatibility when using TR21-4 threaded bottles with applicable systems. Please verify thread specifications before purchase. Wide application: This CO2 brass cylinder adapter is compatible with most TR2 standard CO2 bottles available on the market (confirm bottle thread type prior to use). Ideal for users requiring connectivity with compatible systems. Its compact design also supports use in outdoor settings. Color: Yellow & Red Material: Metal Package Contents: 1 x connector with cap Note: Light reflection and display differences may cause slight variations between the product color in images and actual color. Measurement may vary by +/- 1-3 cm.