Hoya RM90

The 50x50mm square fits my filter holder perfectly, and at 3mm thick it feels substantial without being awkward. Worked exactly as needed for my infrared setup, which is all I really wanted.

Came as a solid 3mm thick square, heavy enough to feel durable when inserting into my filter holder. It blocks visible light perfectly for infrared shots.

Ordered this to swap into my infrared rig and the 3mm thickness sits perfectly in my holder without any wobble. Cutting out visible light while passing IR is exactly what I needed for my modified camera work. Build quality feels solid for the price.