Instruction: Parse the product information to locate the target attribute, and then provide the extracted value of the target attribute and its source in the output, specifying None if the attribute is not present.

Input:
Product title: Sibba Women's Classic Canvas Slip-On Flats Shoes Casual Shoes(Black,7.5 B(M)US)
Product feature: Product Dimensions: 10.2 x 9.5 x 3.9 inches, Shipping Weight: 1.3 pounds, ASIN: B017R20V4S, Date first listed on Amazon: September 12, 2016, Average Customer Review: 3.0 out of 5 stars 1 customer review
Product brand: Sibba
Target attributes: Silhouette
Answer: attribute: silhouette
value: flats
source: product title