How does a panarello work?

A panarello is an accessory for an espresso machine. It is part of the steam wand that is used to "Froth" milk for drinks such as cappuccino or macchiato. It is also used to steam milk for these drinks and for latte. Normally, it takes a degree of skill and practice to properly froth and steam milk without blowing big bubbles in the milk. A panarello attachment helps. It is attached to the end of the steam wand. Steam is passed through the steam wand by the boiler in the espresso machine and comes out the end of the panarello. The panarello entrains, or incorporates, small volumes of air into itself and passes this air through its far end, which is immersed in milk in a frothing pitcher. It still takes practice and skill to obtain perfectly frothed milk of the appropriate temperature (155-160F) but it is easier than without a panarello.