Joinwit adopts the FBT technique to produce the SM coupler with the high performance and liability which achieve the advanced level of similar products in the world. The extremely low excess loss greatly increases the coupler's liability and long-term stability. Joinwit adopts the unique craft to eliminate the reflection of the 1X2 coupler's spare input fiber end and ensure its long-term stability and at least 60dB directivity. Joinwit also supply the 1XN (NXN) Tree/Star type coupler by grade-connection 1X2 coupler.