Most Manhattan towers keep one plan per line from the first residential floor to the top. The Anthem does not. The configuration changes at floor 18. If you are comparing a mid-rise unit to one on 20, read both floor plans. The residence number alone will mislead you.

Line 04 is the proof
Line 04 is a studio of 480 square feet on floors 5 through 17. On floors 18 through 22 it is a two-bedroom of 797 square feet. Floor 23 is a three-bedroom of 1,710 square feet. Floor 24 is a three-bedroom of 1,624 square feet. The last two digits stay 04. The apartment does not.
That is why a search for "04" on a listing site is not a search for one product. You are looking at four products that share a hallway label.
What to ask on the tour
Ask for the PDF of the unit you will sign, not a cousin on another floor. Ask whether the line you like is the pre-18 plan or the post-18 plan. If the leasing office walks you through a model, confirm the model is the same configuration as the available residence. A staged two-bedroom on 19 does not describe a studio on 12.
Ceiling height, exposure, and finishes can also differ by floor even when the room count holds. Those notes are on the listing and the plan. They are not implied by the line number.
How to shop the change
If you need a studio, you are shopping floors 5 through 17 on line 04, not the teens as a group. If you need a two-bedroom on that line, you are shopping 18 through 22. Do not let a vacant unit on the wrong side of 18 waste a Saturday. Filter listings and tour the plan you mean. Call (212) 684-3222.
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