What type of product is primarily used to shorten hair during cutting?

The primary function of products designed to shorten hair during cutting relates to the tools' specific purposes and techniques. Hair thinning shears are specialized scissors that have one or more notched blades to remove bulk and texture from the hair while still allowing length to remain. This technique can reduce hair volume, make the cut less blunt, and create a softer appearance, which is fundamental in achieving layered or textured hairstyles.

Scissors are a general-purpose cutting tool used for a variety of cuts but do not have the same specialty for texturizing. Razors can also be used to create layers and texture, but their primary function is to change the edge of the hair cut, giving a different finish rather than primarily shortening hair. Clippers are intended to cut hair short or to buzz styles and do not provide the precise control and texturization that thinning shears offer.

Thus, hair thinning shears are the most appropriate choice for shortening hair with a more focused impact on texture and volume rather than simply cutting length.