Display Common Item Name in Group Header

Dear Experts,

Can you please tell me that how i can display common text in particular field in Group Header ?

For Example :

I have an one Field : ItemName

In this ItemName field there are an multiple names are available.

Like,

1) Push Button 2B

2) Xenon Push Button 3B

3) Herier Push Button 4C

I want to display "Push Button" as an Group Header.

I think you all are understand my exact requirement.

Thanks & Regards,

Nishit Makadia