An alkaline A is still available. It is the Duracell Procell PC12A. It is intended as a substitute for a mercury A. Mercury A's were slighty smaller(about 1mm) then c-z A's. By the way, there is often confusion about the terms A,B,C etc. batteries. In the past there were A,B, and C radio batteries and A,B,C etc. dry cells. The two groups are unrelated. A radio batteries were used to heat the vacuum tube filaments in early radios. The earliest radios often used 6 volt car batteries, while compact portables of the 40's and 50's often used multiple C or D cells as their A batteries. B radio batteries are high voltage, most commonly 22.5 45, 67.5 or 90 volts. Eveready still makes several sizes of them. On the other hand, B cells are size used in 4.5 volt European bike-light and flashlight batteries.