Dielectric Mirror, 1.25 Inch 90-degree Dielectric Mirror Diagonal for Telescope

I had bought the SVBONY one but had an issue with inserting eyepieces due to the brass clamping band edges catching on them (quality control issue I guess). I was going to try exchanging but found this instead that looks exactly the same but unbranded. The clamping didn't cause trouble and it is otherwise the same thing at a lower price.

Compared to the generic diagonal which was half decent there was a definite loss of light good quality build good optics but for some reason there is definitely a loss of light

From what I can tell this is an unbranded Svbony diagonal. At the time I ordered it was 1/3 the price of the Svbony. It has worked well for me so far and does not seem to hinder my telescope in any way. Optical clarity seems great, it's all metal, and has a compression ring that holds tight.

Didn't come with thumb screw for holding the eyepiece.

I took out the diagonal and hooked the eyepiece straight to the visual back and suddenly everything was 1.5x the brightness!