Most of the red dot sights listed here take one CR2032 coin battery. Some Holosun and SIG SAUER models take a CR1632 or CR1620 instead.
Who made the sight?
Which model?
The battery it takes
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Red dot batteries by model
Red dot sight batteries by maker and model
Maker
Model
Battery
Holosun
HS507C-X3, HS407C-X3, HS507COMP
CR1632
Holosun
EPS-CORE-RD-MRS
CR1620
Holosun
HS510C, HS515CM, AEMS-CORE-X2-RD
CR2032
Holosun
SCRS-RD-MRS
Built-in rechargeable, with solar
Vortex
Crossfire II Solar, Venom Enclosed, Defender-ST
CR2032
Vortex
AMG UH-1 Gen II (holographic)
CR123A
SIG SAUER
ROMEO-X Compact
CR1632
SIG SAUER
ROMEO-M17
CR2032
Aimpoint
Acro P-2, Duty RDS MR
CR2032
Trijicon
RMR Type 2, RMRcc, RCR, MRO
CR2032
From each maker’s product pages. Other models may take a different battery.
CR2032, CR1632 and CR1620 sizes
The digits give the size. Energizer’s datasheets put a CR2032 at 20 x 3.2 mm, a CR1632 at 16 x 3.2 mm and a CR1620 at 16 x 2 mm, diameter by thickness. All three are 3 V lithium coin cells, so use the code the sight’s maker names.
CR203220 x 3.2 mmCR202520 x 2.5 mmCR201620 x 1.6 mmCR163216 x 3.2 mmCR162016 x 2 mm
Ringed: the CR2032, CR1632 and CR1620, side on and to scale. The CR1632 is as thick as a CR2032 but narrower.
Top-loading sights
Trijicon loads the RCR’s battery from the top of the sight.
Keep coin batteries away from children
The National Capital Poison Center says that if anyone swallows a battery, immediately call the 24-hour National Battery Ingestion Hotline at 1-800-498-8666 or your poison center at 1-800-222-1222. Don’t delay. Immediate treatment decreases severity.
Common questions
Do I have to re-zero a red dot after changing the battery?
No, for the Venom Enclosed, Defender-ST and ROMEO-X Compact. Vortex says the Venom's side-load and the Defender-ST's top-mount battery change without re-zeroing, and SIG SAUER says the same of the ROMEO-X Compact.
From Holosun, Vortex, SIG SAUER, Aimpoint and Trijicon product pages, Energizer’s coin cell datasheets and the National Capital Poison Center, read on October 25, 2026. Checked against published data from Energizer, National Capital Poison Center, Holosun, Vortex Optics and SIG SAUER (plus 2 more).
See all 9 sources
Energizer, CR1620 product datasheet (PDF)
Energizer, CR1632 product datasheet (PDF)
Energizer, CR2032 product datasheet (PDF)
National Capital Poison Center, Button battery ingestion (poison.org/battery)
Vortex product pages: Crossfire II Solar Red Dot, Venom Enclosed Micro Green Dot, Defender-ST Micro Red Dot, AMG UH-1 Gen II Holographic Sight
SIG SAUER product pages: ROMEO-X Compact and ROMEO-M17
Aimpoint product pages: Acro P-2 and Duty RDS MR
Trijicon product pages: RMR Type 2, RMRcc, RCR and MRO
Battery sizes come from battery makers' datasheets and device makers' own manuals and help pages. Check your device's manual or the old battery before you buy. If anyone may have swallowed a battery, call the National Battery Ingestion Hotline at 1-800-498-8666 or your poison center at 1-800-222-1222 straight away.
