This 4" starter kit gives you everything you need for using your  Porter Cable or simular Dual Action Polisher with 4" pads. You get,

• (1) 3.5" Backing Plate (5/16-24 thread)

And your choice of any three 4"(Lake Country),

• Yellow Heavy Cutting Pad 
• Orange Mild Cutting Pad or,
• White Polishing Pad or,
• Green Polishing/Finishing Pad or,
• Black Finishing Pad or,
• Blue Final Finishing Pad.