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: Lexar 8 GB 400x Flash Memory Card LCF8GBCTBNA400
Product description: The Lexar Professional 400x CompactFlash memory card provides reliable, professional-level high-speed performance, with a minimum guaranteed speed of 400x (60MB/s), so you can capture and store high-quality images and video with your DSLR camera. The Lexar Professional 400x CF card is available in 8GB, 16GB, and 32GB capacities.
Product feature: Impressive high-speed performance - 400x (60MB/s) minimum guaranteed speed, Capture and store high-quality images and video with your DSLR camera, Significantly improves transfer speeds from card to computer, reducing post-production time, Includes downloadable Image Rescue 4 software to recover lost or deleted photo and video files, Compatible with UDMA CF and CF devices, Free dedicated professional technical support, Limited lifetime warranty
Product brand: Lexar
Target attributes: Format
Answer: attribute: format
value: cf
source: product description
attribute: format
value: compactflash
source: product description
attribute: format
value: cf
source: product feature