AMHsix, the one you want is the 617F (assuming your serial number falls into the correct range). The "F" denotes the constant on/off switch.
I would order from Lagger Pro, but if you do decide to order from Botach, make sure you call first and ask them if they have the Responder 617F in stock. Otherwise, you may be in for a very long wait.
Justin
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Justin T. Huang, Esq.
late of Kennett Square, Pennsylvania