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: Moto Metal MO961 Triple Chrome Plated Wheel (18x9"/6x139.7mm, +18mm offset)
Product description: Moto Metal is for the brave. Those who naturally stand out and follow their own rules. Strength and durability with an irreverent style is what drives us. We dont want to be for everyone. Moto Metal originated in the Southern California Motocross community. With an attitude of Ride Hard, Live Hard the line is inspired by riders and teams alike. Moto Metals edgy designs and street looks collide for a unique look for todays lifted trucks and SUVs.
Product feature: Available in 18 and 20 diameters with various widths and off-sets, Triple chrome plated finish and center cap, Lifetime structural and a one-year finish warranty against peeling or lifting of finish, Lug nuts are not included with wheel purchase, Pictures are meant to show the style of the wheel not necessarily the bolt pattern please refer to product specifications below for exact product information
Product price: $316.89
Product brand: Moto Metal
Target attributes: Diameter
Answer: attribute: diameter
value: 18x9"
source: product title