Instruction: Extract the value of the target attribute from the given product information and output it along with the corresponding source.

Input:
Product title: Top Knobs M823-7 Somerset Finial Appliance Pull Pewter
Product description: Somerset Finial Appliance Pull 7" (c-c) - Pewter Antique, Finish:Antique Pewter, Size:7' Center-to-Center Our Somerset Collection creates a seamless transition between classic and contemporary.
Product feature: Center to Center: 7" - Height: 1" - Length: 10.125" - Projection: 2", Appliance Pulls Category, Antique Pewter Finish, Classic Style
Product price: $43.74
Product brand: Top Knobs
Target attributes: Knob Shape
Answer: attribute: knob shape
value: None
source: None