MK3 Harness This is a superb high-performing harness with ergonomic properties developed from advanced back-packs, and a unique variety of adjustment options to optimize both fit and comfort. The Mk3 is an enhanced version of the Besea Advanced harness. We have made the shoulder straps narrower and integrated the waist belts and lumbar support in to one belt with the same ergonomic advantages but a better fit. All Poseidon Besea wings can be mounted, and you no longer need to use screws. Available in two sizes: Standard (M) and Large (L). The difference between the two sizes is the length of the waistbelt and the number of 40 cc holes (3 rows for Standard and 6 for Large). •Ergonomic harness •40 cc system •Fits most sizes •Available in Standard and Large