Calumet Roll Holder Model C2 (6x7) brand_Peak This extension tube provides a

This extension tube provides a slightly inexplicable 200mm extension for LTM/39mm threaded lenses

Toss in batteries and you get metering functionality

probably not this one

with some paint and finish wear

but excellent functionality

Calumet Roll Holder Model C2 (6x7) brand_Peak This extension tube provides aThe Calumet Roll Holder C2 is a rollfilm back for 4x5 cameras designed to slip in front of the groundglass like a sheet film holder unlike most rollfilm backs that require partial disassembly, causing a condition known as "pain in the butt." This back shoots 10 6x7cm frames on standard 120 rollfilm. In excellent condition, with minor cosmetic wear.