They come in various shapes, varying on inner diameter, outer diameter, and length. Smaller connectors may tend to be lower voltage, but that's certainly always

They come in various shapes, varying on inner diameter, outer diameter, and length. Smaller connectors may tend to be lower voltage, but that's certainly always true. There are several standards, and at least some of them specify voltage ranges for particular sizes, but there's no universal standard. List of plug sizes and their common uses: https://en.wikipedia.org/wiki/Coaxial_power_connector#Listing_of_DC_coaxial_connectors https://en.wikipedia.org/wiki/Coaxial_power_connector#Listin...