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: Mens Hanes 4 Pair Classics Stretch ComfortFlex Boxer Briefs - 7792P4
Product description: Hanes Classics Boxer Briefs. Made with super soft, premium cotton, Hanes Classics is our most comfortable. Hanes Classics also feature a premium waistband for plush, all-day comfort.
Product feature: cotton, briefs-underwear closure, Comfort Flex waistband keeps its shape wash after wash., Tag-free for itch-free comfort., Fabric wicks away moisture to keep you comfortable no matter what the day brings., Leg bands that won`t ride up guaranteed., Available in a convenient 4-pack of assorted colors., Product Dimensions: 13 x 8 x 1 inches, Shipping Weight: 11.2 ounces, ASIN: B004CTP5VY, Item model number: 7792BG, Date first listed on Amazon: January 18, 2012, Average Customer Review: 3.8 out of 5 stars 91 customer reviews
Target attributes: Silhouette
Answer: attribute: silhouette
value: boxer briefs
source: product title
attribute: silhouette
value: boxer briefs
source: product description