Condition: Very good.
The Takahashi TCD0774 Spacer connects various Takahashi telescopes and adapters to QSI Series 500/600 series WSG with the STL thread faceplate.
This adapter has a male M54x1.0 Takahashi Wide T thread on one side and a male 2.156"-24 TPI STL thread on the other. It is not compatible with T-thread faceplate cameras.
Note that this item is discontinued, available today perhaps only on the used market.