SINUS LIFT OFFSET TYPE, CONCAVE TIP. MARKED AT 8-10-13-15-17 &20MM, AND 8-11-13-15-17 AND 20MMAll SLO-F Osteotomes are the concave tip style. Sizes2.6, 3.0,and 3.1mm are marked at 8-10-13-15-17 &20mm. Sizes 3.8, 4.0, 4.5, 5.0, 5.5 and 6.0 are marked at 8-11-13-15-17 and 20mm. The mm marking is stamped in the end of each handle for easy identification.