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: Vertigo 2GB mp3 Player
Product description: Small portable mp3 player which holds 2 gigabytes of music. Includes: -mp3 player -earphones -charger/sync cable -instructions
Product feature: Small portable mp3 player which allows you to take 2gb of music wherever you go!
Product price: $20.23
Product brand: VertiGo
Target attributes: Screen Size
Answer: attribute: screen size
value: None
source: None