“k-tas” might be an abbreviation of “komplektas”.
In English, “kit” is often used as a unit of counting goods, mechanical parts, stock items, etc.


DLKŽ:
komplektas
1. vienos paskirties daiktų rinkinys: “Darbo įrankių k.”, “Metinis laikraščio k.”

Wiktionary:
kit
4. Any collection of items needed for a specific purpose, especially for use by a workman, or personal effects packed for travelling.
“Always carry a good first-aid kit.”
5. A collection of parts sold for the buyer to assemble.
“I built the entire car from a kit.”