The model number of your Philips headphones can be located in different places depending on the type of the headphones. Find out where to find the model number here:
In-ear headphones
For in-ear models of headphones, the model number is located on the stopper. See the figure below
Other types of headphones
The location of the model number depends on the design. It may be located on the stopper, the inner or outer side of the headband, the cable plug, or on the earpiece. Below are some examples.