
The PolarPro QuartzLine Step-Up thread conversion ring is made of a brass alloy, which is just the right amount of hard to be durable and, on the other hand, it is a flexible material, so the adapter ring can withstand tightening and will not shear off like aluminum adapters can.
The adapter ring allows you to attach a larger filter to the lens' filter threads. This converts the 67mm thread to an 82mm thread.
So you can use the larger special filter you already have on a lens with a smaller thread size. There's no need to buy a high-quality special filter in a different size, for example, one filter and a thread adapter like this will do the job! Savings!
The first number in the product name is the male thread, i.e. the size of the lens thread, and the second number is the larger female thread, i.e. the size of the filter to be used, for example.
The adapter is treated with a matte finish to reduce reflections, a feature that is important for long exposures. The outer surface of the ring has serrations that make it easier to attach and remove the adapter.