Which Item type i should select to control 1way RF switch?

I use 1way RF relays, it supports 3 commands ON, OFF & SWITCH (this switches from one state to another)
And another has a dimmer and supports 4 commands ON, OFF, SWITCH, LEVEL (level 0 - is OFF).
Which Item type i should select to control this relays?

If you use a Switch item for the RF relay that supports ON, OFF and SWITCH, you will lose the ability to explicitly send the SWITCH command, but the REST API and CMD servlet both support TOGGLE commands to Switch items, that uses existing state to send the opposite command.

I would use a Dimmer item for the second device, because you can send Dimmer items either OnOffType or PercentType commands.

Can i use String type Item for this relays?
Like this:
String Light_1 "Light_1" { mqtt=">[wb:/light1:command:OFF:0], >[wb:/light1:command:ON:1], >[wb:/light1/switch:command:SWITCH:1] ", autoupdate="false" }

I think that should work, too, except you are sending the same “1” for both ON and SWITCH.

for SWITCH is /switch mqtt topic.

Ah, missed that!