John Gill Commentary 1 Chronicles 2:50

"These were the sons of Caleb, the son of Hur, the first-born of Ephrathah: Shobal the father of Kiriath-jearim," — 1 Chronicles 2:50 (ASV)

These were the sons of Caleb the son of Hur, the firstborn of
Ephratah
This is another Caleb, the grandson of Caleb the son of Hezron, called after his name; he was the son of Hur, the firstborn of his wife Ephratah, (1 Chronicles 2:19) .

Shobal the father of Kirjathjearim :
of the inhabitants of that place; they sprung from him; or, as the Targum, he was prince of Kirjathjearim, a city in the tribe of Judah, (Joshua 15:60) .