K&F Concept 37–40.5 mm Step-Up Ring, 2 pcs + Cleaning Cloth

The K&F Concept 37–40.5 mm step-up ring lets you fit filters, lens hoods and other 40.5 mm accessories to a lens with a 37 mm filter thread. You can use one set of larger filters on smaller lenses too, without buying filters for every diameter. The package contains two identical rings made of aviation-grade aluminium alloy and a microfiber cleaning cloth.

Larger filters on a 37 mm lens

The ring screws into the filter thread of the lens (37 mm), and a filter – ND, CPL, UV or any other – screws into its 40.5 mm outer thread. If you bought filters for your largest lens, the ring lets you use them on smaller ones too. Two identical rings are handy if you have two lenses with the same thread or want to keep one as a spare.

Aluminium alloy with a matte finish

The ring is made of aviation-grade aluminium alloy: it is light, strong, corrosion-resistant and does not deform. The surface is oxidised and sandblasted to a matte black so it does not reflect stray light into the lens. The precision-cut thread screws on and off without binding.

How to find your thread size

The filter thread diameter is printed inside the lens cap or on the lens barrel. The first number in the ring marking is the lens thread, the second the filter thread. The ring suits lenses with a 37 mm thread and filters and accessories with a 40.5 mm thread.

Cleaning cloth

A microfiber cleaning cloth comes with the rings. It is gentle, does not shed fibres and cleans filters and optical glass without streaks or the risk of secondary contamination.