(a) The economic retention limit may be increased where:

(1) The item is of special manufacture and relates to an end item of equipment which is expected to be in use beyond the economic retention time limit; or

(2) Costs incident to holding an additional quantity are insignificant and obsolescence and deterioration of an item are unlikely.

(b) The economic retention limit should be reduced under the following conditions:

(1) The related end item of equipment is being phased out or an interchangeable item is available; or

(2) The item has limited storage life, is likely to become obsolete, or the age and condition of the item does not justify the full retention limit.