100 Beachhead challenge completion --> Needs to be T15 or T5/T10 ?

Hi,

Three variants of the Beachhead map exist : T5, T10 and T15 :
https://pathofexile.gamepedia.com/The_Beachhead

For the "100 Beachheads" challenge completion, is it necessary to use T15 only, or does it work also with lower tiers ?

Please no assumptions, answer only if you are sure by having tested yourself, or if you can provide an official source.

Thank you !

Only works with T15 and you only need 50, not 100.

Lower tiers don't add numbers to the completion.

You're right it's 50, ty !