This Standard covers general and dimensional data for the following general purpose tapered and reduced cross section retaining rings: a) External Type NA1, Internal Type NA2, and E-Ring Type NA3 b) Heavy Duty External Type NA4, Reinforced E-Rings NA5, C-Rings Type NA6 c) Bowed External Rings NA7, Bowed Internal Rings NA8, Bowed External E-Rings NA9 d) Inverted External Type NA10, Inverted Internal Type NA11, Beveled External Type NA12, Beveled Internal Type NA13 e) External Self-Locking Rings Type NA14, External Interlocking rings Type NA15, External Bowed Locking Prongs Rings Type NA16 The data my used with the nominal size shafts and housings listed and in grooves of the recommended dimensions listed herein. Also included are formulas and tolerances on which dimensional data are based. Three appendices include guidance for assembly and recommended standard drawing formats. The inclusion of dimensional data in this Standard in not intended to imply that all of the products described are stock productions sizes. Consumers should consult with suppliers concerning lists of stock production sizes. B18.27-1998 is a consolidation and update of B18.27.1, Part 1 External Type - NA1; Internal Type NA2; E-Ring Type - NA3; B18.27.2, Part 2 Heavy Duty External - NA4; Reinforced â??Eâ?? Rings - NA5; â??Câ?? Type Rings - NA6; B18.27.3, Part 3 Bowed External - NA7; Bowed Internal - NA8; Bowed External â??Eâ?? - NA9; B18.27a-1999 addenda added in B18.27.4, Part 4 Inverted External NA10, Inverted Internal NA11, Beveled External NA12, Beveled Internal NA13 B18.27b-2000 addenda added in B18.27.5, Part 5 Type NA14 - External Self-Locking Rings; Type NA15 - External Interlocking Rings; Type NA16 - External Bowed Locking Prongs Rings This publication is issued with an automatic addenda service. All addenda service publications are issued in loose leaf format to facilitate later insertion of replacement pages which incorporate the latest approved changes to the standard. Purchasers may wish to purchase a binder from ASME (ASME Binder), but the publication will also fit a standard three ring binder. Details on the specifics of the addenda service are as follows: