Back when you first asked about this (in another thread several months ago), there was general agreement (with the agreement of at least one native speaker of Irish) that Beanna Beola is correct, but at least one fluent speaker and some sources I checked do have Na Beanna Beola, so you can choose either. There isn't much more that can be said about this.

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I'm not a native (or entirely fluent) speaker, so be sure to wait for confirmations/corrections, especially for tattoos.

As I said in the previous thread "Na Beanna Beola" is what they are called locally.
Maybe the "Na" is used because it is a geographical name- like a lot of other mountain ranges in Ireland. But I think it would be correct without the definite article too.

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It is recommended that you always wait for three to agree on a translation.
I speak Connemara Irish, and my input will often reflect that.
I will do an mp3 file on request for short translations.
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Máirtín Ó Direáin wrote several times "na Beanna Beola" in "Feamainn Bhealtaine". So I guess it is OK

Bríd is a native speaker who lives in the Conamara Gaeltacht, so I'd say you're good to go here, solidrock.

Redwolf

Thank you everyone!!