This SAE Recommended Practice covers flexible cellular rubber products known as sponge rubber and expanded rubber, but does not apply to latex foam rubber or ebonite cellular rubber. The base material for an open/closed cellular product may be made of synthetic, natural, reclaimed rubber, or a mixture, and may contain other polymers or chemicals, or both, which may be modified by organic or inorganic additives. These elastomeric materials have properties similar to those of vulcanized rubber, namely (a) the ability to be converted from a thermoplastic to a thermosetting state by crosslinking (vulcanization) and or (b) substantial recovery of their original shapes when strained or elongated, or both. Extruded or molded shapes of sizes too small for cutting standard test specimens are difficult to classify or test by these methods and will usually require special testing procedures. In case of conflict between the provisions of this general specification and those of detailed specifications or test methods for a particular product, the latter shall take precedence. Reference to the test methods in this document should specifically state the particular test or tests desired. The values stated in SI units are to be regarded as the standard. English units are included for reference only. The following safety hazards caveat pertains only to the test methods portions of this document: This document does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this document to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.