Precision ground metallic O.D. with a lead-in chamfer to help ease the installation
Metallic seals do not have the ability to seal around the O.D. like the rubber covered seals, they can promote fretting/galvanic corrosion and are therefor not as kind to softer housing materials
The metallic casing enables easier fitting than rubberized seal types, however, this type of seal demands closer tolerances in the housing bore to ensure proper sealing on the outer covering
Competitors equivalent suffixes: TB, B1SL, DFS, BSL, BC, WBS, BES, CRWA1, Type 47, Model 78, B1USL