This is one gel ink refill for the Pilot Hi-Tec-C Coleto writing system. 

The Pilot Hi-Tec-C Coleto is an upgrade of the classic Hi-Tec-C gel pen which is loved by artists, designers and students thanks to its precise needle-point tip and smooth ink. It is convenient as it is a multi pen system that can be customized according to personal preference. Users can combine ink colors, erasers, mechanical pencil components and styli desired. 

Users should make sure the small fins on either side of the component's plastic push button lines up with the grooves on either side of the component slot in the pen body when installing the Hi-Tec-C Coleto refill.

Disclaimer: The pen body is sold separately.