Ebay Measuring help please !!

[PooohBear]

Hi everyone !!!
I know maybe you think this is a dumb question... but, a person is asking me to measure something i'm selling, they want to know the measurements from armpit to armpit...... ummmm, where and what exactly do I measure !?

 

[patsal]

under sleeve arm to under under sleeve arm

looks like they want a chest measurement from the same way they are measuring at home?

 

[PooohBear]

Thank You !!