How to tell which dynamic control sent to an event?

This is my first attempt at working with dynamically created controls.

I have created a class object cControlEvent with the following code. (I cut out the code not pertaining to the checkbox)

Public WithEvents CHK As MSForms.CheckBox


Private Sub CHK_Change()
   ** tell me which box was changed **
End Sub

in the code module, I have the following code:

Dim CHK_Evts As New Collection 

sub Form_Builder()

**non relevant code deleted****
    Set Evt = New cControlEvent
    If i_Columns = 1 Then
        Set Evt.CHK = ctl
        CHK_Evts.Add Evt
    Else
**  more code**
    End if
end sub

What do I need to change/add to be able to get the name of the control that is firing off the change event?