The Honeywell 40003918-007 has two uses:
1) As a conversion kit to use a new 40003916-003 replacement powerhead on an old style (pre 1986) V4073 motorised valve.
A motorised valve that does not require this kit can be identified by a bump on the top of the powerhead.
2) Used to replace the innards on new style V4073A valve bodies. For example where the valve body is sticking or seized.
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