RadioRa2 device selection

Hi everyone.
I am Electrical contractor and I'm facing a challenge with a customer's residence who has the RadioRa2 system installed for lighting control.
I needed to replace some lighting fixtures and the customer have chosen a 110v 4w LED light bulbs to replace the existent halogen ones. That LF is controlled by the wall dimmer model RD-RD.
I would need to find an equivalent dimmer to control those LED lighting bulb because they works if I put at least one halogen light bulb on the lighting fixture which has 10 lighting bulb in total.
If I don't do that there is not brightness control at all.
The customer doesn't want to keep one halogen and 9 LED lighting bulbs, so I need to find some compatible solution with the existent system.
Please find attache picture.

Thank you very much for any help with that.

You've identified the wrong component to change out- that's a "companion dimmer" and it's not the actual dimmer you need to swap out.
Somewhere else on the circuit is the actual dimmer- it could look like the RD-RD or it could be a keypad that has a dimmer on the backend. If it's a keypad, check to see if there is a neutral connection on the keypad available and if so connect it to neutral. That could be an easy fix to your problem. More likely, you are going to find a RRD-6D with no neutral connection.
Lutron has a LED selection tool at their website that can help with seeing if a particular dimmer works best with this LED lamp. I'm going to guess a RRD-6NA would probably work fine once properly configured.
Once you've swapped out the dimmer, you'll need to activate it on the Ra2 system. You might be served best by calling Lutron to find a programmer in your area that can help out with that, if you aren't set up to change programming on the main repeater.

Hi digit1
Thank you very much for your answer.
You know, I have forgotten to tell you that LF is on a three way circuit with two devices.(dimmers).
The first one is like a picture I sent you, the second one is exactly the same model RD-RD, but it doesn't have the bright indicator and none of them has neutral connected. The customer is using a handheld remote control "CONTR0L4" and there is no keypad with dimmer on the back nearby.
So it seems to be that the dimmers, as you suggest me need to be model RRD-6NA.
Regarding this dimmer I would like to understand some of the spec that became confuse for me.
For example the mentioned Dimmer one spec said:3-wire Fluorescent/LED (120-277V).
When "Led" is mentioned what type of led is referring to ?
Is it saying you need to connect LED driver or you can connect those LED retrofit light bulb which manage 110 v and has the driver inside?
I will appreciate very much for your help on that.
Best regards,
Radio777

And bear in mind that a RD-RD may be one of several on an N-way kind of circuit. They're just 'slaves' to the actual dimmer. They're not acting the same as regular 3-way switches. They're able to use that sort of wiring (travelers) but they don't do the switching in them. All that is handled back at the controlling dimmer.

If all you've found are two RD-RD devices then you have not found the actual dimmer controlling the load. So, no, you cannot swap out an RD-RD for an actual dimmer. You need to find the dimmer actually controlling those lights. Is it one of the others in the box? A simple way to check is to pop-out the air-gap button on the front of an actual dimmer. That'll break the circuit.

I have one house with a 10ND controlling some outside spot lights. The dimmer is in the master bedroom on the second floor (closest to the first of the outside spots). There are two other RD-RD at entry doors on the first floor. So nothing in either of those boxes is controlling the actual load. It'd be a bit of a bug-hunt for anyone to figure that out if they didn't think like the architect that laid out the wiring plan.

Calling Lutron's 800 number for support is worth doing, they do understand how to walk electricians in the field through most of this.

Depending on the size of the system you could do the re-programming but this is not a trivial jump-in-and-do-it kind of thing. The best question to ask the homeowner is who did the initial programming? Work with them as they're going to have the programming source project used to set it up. Otherwise you open up a can of worms that may take several hours to resolve.