4-102978-0-20 vs 4-102978-0-21 vs 4-102978-0-22

PartNumber	4-102978-0-20	4-102978-0-21	4-102978-0-22
Description	CONN HEADER R/A 20POS 2.54MM	CONN HEADER R/A 21POS 2.54MM	CONN HEADER R/A 22POS 2.54MM