Instruction: Using the product's title, description, features, price, and brand, identify and retrieve the values associated with a specified set of target attributes. Output the extracted values along with their respective sources (e.g., title or feature) indicating where each value was found.

Input:
Product title: Impac Crosspac 26" x 2.0 Mountain Bike Tyre
Product description: Impac is the name of Schwalbe's economical tyre range that have been produced to compete with cheaper brands but whereas the quality isn't normally very high with cheaper brands these are good quality at great prices. The Impac Crosspac tyre features a design that has been inspired by Cyclocross tyres, with a low profile tread pattern for fast rolling and low resistance in a straight line. Features: 26" x 2.0 54-559 2.0-4.0 Bar 30-60 PSI
Product feature: 26" x 2.0 mountain bike tyre, Great quality at fantastic value, Fast rolling low profile tread pattern, Inspired by Cyclocross tyres, Impac branded by Schwalbe
Product price: $16.08
Product brand: Impac
Target attributes: Size
Answer: attribute: size
value: 26"
source: product feature
attribute: size
value: 26"
source: product title