Abstract: A baseball or softball bat which enables a ball to fly farther than a conventional bat. The bat is made of metal, wood or carbon fiber-reinforced plastic and its cylindrical ball-hitting part has an axial cross section shape as follows: a lot of concave-surfaced grooves and convex-surfaced ridges are arranged in parallel alternately along the circumference of the bat and the convex parts are round and curved outward. The concave and convex parts are covered by a cylindrical sheet of polyurethane elastomer or similar material. Also, a metal baseball or softball bat is manufactured by grooving the cylindrical ball-hitting part surface by a lathe using a roller.

Abstract: An electrically-conductive fine particle powder comprises fine, hollow spherical particles of non-magnetic material such as glass or resin plated with a metal and having a bulk density of 0.2 to below 0.9 g/cm.sup.3. An exothermic electrically-conductive coating or paste comprises the above powder and a synthetic resin binder. An electrically-conductive heating unit is formed from a suitably shaped solid or solid surface coated or impregnated with the above coating or paste and is operable at low voltages.