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: DR Strings Electric Guitar Strings, Dimebag Darrell Signature, Treated Nickel-Plated, 11-50
Product description: Gauges 11-14-18-28-38-50. The Dimebag Darrell signature Hi-Voltage electric guitar strings stay in tune and remain bright and fresh for a long time. DR Hi-Voltages are made for string bends, whammy-bar dives, harmonic screams, and chunky riffs. The Dimebag Darrell signature Hi-Voltage electric guitar strings stay in tune and remain bright and fresh for a long time. DR Hi-Voltages are made for string bends, whammy-bar dives, harmonic screams, and chunky riffs. "I've been playin' the strings of strength since 1995. I like the way DR Strings feel and react, you can really get a grip on them. They're great for everything, from big ol' string bends, to huge whammy bar dives, perfect for blood curdling harmonic screams and just straight out heavy chunky riffin'. They also stay in perfect tune and remain fresh and bright for an amazingly long time" said Dimebag. Gauges 11-14-18-28-38-50.
Product brand: DR Strings
Target attributes: Core Material
Answer: attribute: core material
value: electric
source: product title
attribute: core material
value: electric
source: product description