Plates are plastic and the sizes are listed below:
Singles, Outlets, Single Rocker/GFI, Cable Covers, Dimmers Plates, Phone jacks are 2-3/4" x 4-1/2"
All Double Size Plates are 4-1/2" x 4-1/2"
All Triple Size Plates are 6-1/4" x 4-1/2"
All Quad Plates are 8" x 4-1/2"
Phone jacks do come with wire assembly on back, they are not just a cover only.