The Lufthansa RIMOWA Alu 45L is the special edition version of RIMOWA's previous generation Topas Multiwheel 45L. The RIMOWA Cabin Plus is the latest generation of the the current collection.

The RIMOWA Cabin Plus comes in at 57 x 44 x 22.5 cm; Lufthansa RIMOWA Alu 45L comes in at 56 x 45 x 25 cm

United carry-on limit is 56 x 35 x 22 cm.

Lufthansa is 55 x 40 x 23 cm.

The Cabin Plus, or Lufthansa Alu 45L are both in excess of each carrier's stated carry-on dimensions.

However, you will find plenty of FT members have had varying degrees of success in taking this item on-board aircraft.

You will have better luck at newer aircraft with updated overhead storage bins to take the 45L onboard, if you can get it past the gate agent.

If you are traveling domestic or older aircraft, the 45L will risk being gate checked due to being oversized.

Your call.