RH4 Keybed Hammers are Identified by a Letter Designation. There are Four Groups for the White Keys and 4 Groups for the Black Keys. Look for Letters A,B,C,or D on your Hammer and Match it up to the Part Numbers Below
510640520501 WH KEY HAMMER A H30367-WA
510640520502 WH KEY HAMMER B H30367-WB
510640520503 WH KEY HAMMER C H30367-WC
510640520504 WH KEY HAMMER D H30367-WD
510640520505 BK KEY HAMMER A H30368-BA
510640520506 BK KEY HAMMER B H30368-BB
510640520507 BK KEY HAMMER C H30368-BC
510640520508 BK KEY HAMMER D H30368-BD