Asahi M42 Auto Extension Tube Set brand_Manfrotto Vivitar 2x Macro Focusing Teleconverter

Vivitar 2x Macro Focusing Teleconverter for the Olympus OM manual focus lensmount

but I assume that it's some kind of SEO thing

The base attaches to a light stand

Well now you have

Suitable for mirrorless cameras or small-to-mid-size DSLRs

Asahi M42 Auto Extension Tube Set brand_Manfrotto Vivitar 2x Macro Focusing TeleconverterThis Asahi extension tube set includes three M42 thread mount extension tubes: roughly 9mm, 19mm, and 29mm, for a total of about 57mm extension when combined. These are auto diaphragm tubes with a stop down passthrough system. In excellent condition, with only very minor paint wear. Includes original leather case.