The 2014 Easton S4 is available in BBCOR only and makes a great transition bat. Both the S3 and S4 share the one piece construction with a THT 100 Scandium Alloy barrel that offers greater durability and a traditional aluminum feel. The only difference between the two is barrel size. The S3 has a 2 5/8″ barrel where the S4 has a 2 1/4″ barrel offering a faster MOI, making the barrel easier to control.