What is the purpose of the metal plate held by the altar servers at some Masses?

[CapIV]

I have recently been going to a larger Catholic Cathedral as opposed to my usual smaller Catholic church. One thing I noticed that was different was that, during Communion, the altar servers have these sort of metal plates that they hold under the Eucharist as it is being administered. What is the reason for this?

 

[Jim_Blackburn]

The item in question is called a Communion-plate - I remember using one when I was an altar boy in my youth. Its purpose is to catch the host (or some part of it) should it be dropped.

The General Instruction of the Roman Missal (118) mentions it in the section concerning articles to be prepared for Mass:

“The following are also to be prepared… the Communion-plate for the Communion of the faithful”.

Additionally, Remptionis Sacramentum (93) encourages its use:

“The Communion-plate for the Communion of the faithful should be retained, so as to avoid the danger of the sacred host or some fragment of it falling.”