The MFJ-16C01 is a dog bone ceramic glazed center or end insulator. The MFJ-16C06 is a six-pack of dog bone ceramic glazed center or end insulators.
It will not break with long antennas and will not arc over or melt even under full legal power. Molded ridges give an extra long path to prevent high voltage breakdown. Smooth wire holes prevent wire damage.
The 16C01 can be used as a center or end insulator for dipoles, doublets, G5VRs, guy wire, or vees.