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: Sirui P424 Carbon Fiber Monopod
Product description: The lightweight SIRUI P-424 is a carbon fiber monopod that is well suited to provide stability for time-sensitive photography in which the time required to set up a full tripod may cause the photographer to miss the shot entirely. The SIRUI Monopod is constructed of 8x carbon fiber and weighs just 1.3 lbs. When not in use, the SIRUI P-424 folds down to a compact 22 inches. When the four sections of this carbon fiber monopod are fully extended, the unit provides a maximum operational height of 66.9 inches. The SIRUI Monopod is able to support heavier equipment of up 33 lbs on reversible 0.25-inch 20 thread-per-inch and 0.375-inch 16 thread-per-inch screw-on mounting plates. The removable stainless steel spiked foot of the SIRUI Monopod ensures optimum traction on most outdoor terrain. The leg locks are composed of a durable silicone and make use of a twist-function to allow for speedy extension of the leg without the fear of accidental collapse while shooting. The included foam grip provides comfort and security in any temperatures or conditions.
Product feature: Sirui P424 Carbon Fiber Monopod - Wrist Strap - Padded Case - Sirui 6 Year Warranty, Excellent stability when working with long telephoto lenses and in low-light situations, Easy to carry, sets up instantly and is ideal in tight spaces, Include a wrist strap with carabiner and compass, Features 4 sections that extend to 66.9 inches (170cm) when fully opened
Product brand: Sirui
Target attributes: Head Type
Answer: attribute: head type
value: None
source: None