The 23A (A23) used mostly in garage door openers is dry cell  battery. Known by many names such as 23AE, GP23A, V23GA etc. See below for a full list of 23A battery compatibility.

23A Specifications

• Diameter: 10.3mm
• Height: 28.5mm
• Voltage: 12V
• Capacity: 55mAh

23A Battery Compatibility and Cross Reference

• A23
• 8LR932
• 23AE
• GP23A
• GP-23A
• LR23A
• A23GA
• A23S
• BOGP23
• CN23A
• E23A
• EL12
• EXC-23BP
• GP-23GA
• K23A
• MN21
• MS21
• V23
• VR22
• LRV08
• L1028
• P23GA
• RVO8
• 8LR23
• 8F10R
• CA20
• MN21/23
• 3LR50
• WCLR23A
• V23GA
• 1811A
• TR164

The dimensions of a 23A battery is 28.5 mm long and 10.3 mm in diameter, with an average weight of 8 gms.  23A batteries are made up of eight single LR932 batteries stacked in tandem.