John Gill Commentary 1 Chronicles 15:18

"and with them their brethren of the second degree, Zechariah, Ben, and Jaaziel, and Shemiramoth, and Jehiel, and Unni, Eliab, and Benaiah, and Maaseiah, and Mattithiah, and Eliphelehu, and Mikneiah, and Obed-edom, and Jeiel, the doorkeepers." — 1 Chronicles 15:18 (ASV)

And with them their brethren of the second degree
Who were next unto them, both in office and skill in singing:

the fourteen following, Zechariah, Ben, and Jaaziel, and Shemiramoth,
and Jehiel, and Unni, Eliab, and Benaiah, and Maaseiah, and Mattithiah,
and Elipheleh, and Mikneiah, and Obededom, and Jeiel, the porters ;
who, when they were not employed in singing, were doorkeepers of the sanctuary; either they had been porters at the tabernacle in Gibeon, or were so after the ark was placed in the tabernacle David prepared for it.