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: Stance Mens XL White
Product description: Stance Smokescreen boxer brief. Men's underwear. Special fabric nourishes skin is odor resistant and super comfortable. Exposed Core-flex#8482; waistband. Feather-seam#8482; panel construction to reduce stitch irritation. Dual layer pouch give support. Allover print. 100% Butter Blend#8482; milk fabric. Imported. Vendor style #: M300X16SMO.
Product feature: 5% spandex, Imported, Stance Smokescreen boxer brief., Men's underwear., Special fabric nourishes skin, is odor resistant, and super comfortable., Exposed Core-flex™ waistband., Feather-seam™ panel construction to reduce stitch irritation., Product Dimensions: 10 x 12 x 10 inches, Shipping Weight: 5.6 ounces, ASIN: B01BW9SL44, Item model number: 1080209362_M300C16SMO_WHT_L, Date first listed on Amazon: August 15, 2016, Average Customer Review: 5.0 out of 5 stars 2 customer reviews
Target attributes: Silhouette
Answer: attribute: silhouette
value: boxer brief
source: product description
attribute: silhouette
value: boxer brief
source: product feature