Louisville Slugger model R206 was used by Carlos Guillen with the Seattle Mariners most likely during his 2000 rookie season. The bat shows tremendous use and is not cracked. Many ball marks, seam impressions, and ink transfers are visible on the front, right, left, and back barrel surfaces. There is grain swelling from repeated contact with some grain separation present as well. The handle has a light to moderate coat of pine tar and is not cracked. Nothing is written on either end. Guillen has signed the lower front barrel (below the MLB logo) in silver and he added his #8.
An image on Getty shows Guillen in April of 2000 using an LS model R206 of the same finish and labeling. It’s very close to being a photo match, but not all the grain is visible in the photo in order to confirm that it is the same bat.