This SAE Standard covers the basic cigar lighter receptacle, which may optionally incorporate overload protective devices. Figure 1 and Table 1 show the cigar lighter receptacle and its pertinent dimensions. Lighter plugs shall be permanently marked either "6 volt" or "12 volt". Manufacturers of accessory plugs to energize devices such as trouble lamps and razors are cautioned to conform to the provisions given in this document. Live contact of any accessory plug shall be made with the center stud; the contacting member must not be less than 3.56 mm in diameter and have a minimum spherical radius of 2.54 mm at the contacting end. To prevent damage, the body of an accessory plug back of the contact end should be large enough to serve as a centering guide when it is inserted into the receptacle. The contact end of any accessory plug should have sufficient taper so as not to interfere with the receptacle bimetal fingers. Any ground contact fingers should be so designed as not to interfere with, distort, or catch on the grounding lances in the receptacle when the plug is rotated. Wiring capacity and overload protection, as provided by the automotive industry to the 12 V lighter receptacle, restricts accessory plug devices to a maximum current draw of 8.0 A. Accessory plugs shall be permanently marked "6 volt" or "12 volt" in letters 4.7 mm high minimum.