The costumes make great gifts. They are also great for photos or contests. Although the costumes are made to be safe and comfortable and can be worn a long time with supervision, it is recommended that they only be worn for a short time for contests, etc. so they do not get overheated.
Sizing: The guinea pig models wearing the costumes in my photos are full grown (approx. measurements: 8-9" from back of ears to their bottom, 10-11" waist) that will help you judge the size of the costumes. Most costumes will fit an average size adult guinea pig, but measure your guinea pig first to be sure it will be a proper fit. If the guinea pig is too young/small, they will walk out of the costumes.