The main Holosun 515 models look closely related because they share a compact, enclosed, 20mm tube-style format. Their differences become clearer when you look at each configuration individually: the 515GM, 515CM, 515GT and 515CT combine different housing materials with different power features.
The choice comes down to two features: aluminum or titanium housing, and battery-only power or Solar Failsafe. All four models keep the same compact 20mm format.
Holosun 515GM: Aluminum Without Solar
What Defines the GM?
The 515GM pairs a 7075 aluminum housing with a 20mm viewing opening and battery-powered illumination. It is the non-solar aluminum configuration in this comparison. It is a straightforward starting point if you want the 515’s compact size without solar support or a titanium housing.
The enclosed body protects the emitter behind front and rear lenses. Like the other 515 models, the GM has a non-magnified 1x view.
Reticle and Battery
The 515’s multi-reticle system combines a 2 MOA dot and 65 MOA circle, with selectable display options. A buyer who wants that flexibility does not need to choose a solar model solely to get it.
A replaceable CR2032 battery powers the GM. It has no solar panel, keeping the power system simple.
Who Should Start With the GM?
Choose the GM if you want the compact 515 format and selectable reticles in an aluminum housing without paying for solar support.
Compared with the other models, the GM lacks two specific features: a titanium housing and Solar Failsafe. If neither matters to you, another model may not offer a meaningful benefit for your needs.
Reference: Holosun 515GM, with housing details supported by the consumer catalog.
Holosun 515CM: Aluminum With Solar Failsafe
515CM Housing and Solar Features
The 515CM retains the enclosed 20mm format but uses a 6061 aluminum housing and adds Solar Failsafe. It therefore differs from the GM in both its housing alloy and its power options, not just the presence of a solar panel.
The CM keeps the same 20mm viewing window and non-magnified view as the GM. Its main differences are the 6061 aluminum housing and Solar Failsafe.
How to Understand Solar Failsafe
Solar Failsafe supplements battery power in suitable light. The CM still uses a replaceable CR2032 battery, and the panel does not recharge it. Solar support adds another power source without eliminating the need for battery replacement.
The CM has the same selectable dot-and-circle reticle format as the other 515 models. Its solar support is the reason to choose it over a battery-only version.
Where the CM Fits
Choose CM for a compact aluminum sight with Solar Failsafe. Choose CT instead if you also want titanium.
Compare the GM and CM in the same reticle color, with equivalent mounting hardware and accessories. This helps separate the cost of solar support from price differences caused by color or package contents.
Reference: Holosun 515CM.
Holosun 515GT: Titanium Without Solar
Titanium in the Compact 515 Format
The 515GT moves to a titanium housing while retaining the 20mm opening and battery-only configuration. It shows that titanium construction and solar support are separate options; choosing one does not require the other.
If titanium is the feature you want, the GT offers it without requiring the solar-equipped CT. It also keeps the compact 515 format rather than moving to the larger 530 family.
What Does Not Change?
The GT pairs the titanium housing with a replaceable CR2032 battery and the same selectable dot-and-circle reticle format.
Compare the complete sight-and-mount weight if a lightweight setup is important; titanium alone does not determine the total.
When to Choose the GT
The GT is worth considering if you want a compact 515 with a titanium housing but do not need solar support. Compared with the GM, the main difference is the housing material. Compared with the CT, the main difference is the absence of Solar Failsafe.
Check the included mount and accessories before ordering, particularly when comparing prices across different packages.
Reference: Holosun 515GT.
Holosun 515CT: Titanium With Solar Failsafe
Titanium and Solar Support Together
The 515CT combines titanium construction and Solar Failsafe in the compact 20mm format. Choose it when you want both features in one sight.
You keep the smaller 515 body and non-magnified view. For a larger window, the 30mm 530 series is the next family to compare.
Battery, Solar and Reticle
Like the other models, the CT uses a replaceable CR2032 battery. Solar Failsafe supplements its power supply; it does not recharge the battery or eliminate the need to replace it.
All four versions offer a selectable dot and circle. The CT price buys titanium and solar support, not an exclusive reticle.
When to Choose the CT
The CT makes sense if you want both titanium construction and solar support. If only one matters, the CM or GT may be a closer match: the CM combines aluminum with solar support, while the GT offers titanium without solar.
This is the main benefit of understanding all four models before comparing prices. You can choose the combination you want without paying for features you do not want.
Reference: Holosun 515CT.
GM vs CM vs GT vs CT: The Comparison
| Model | Housing | Solar |
|---|---|---|
| 515GM | 7075 aluminum | No |
| 515CM | 6061 aluminum | Yes |
| 515GT | Titanium | No |
| 515CT | Titanium | Yes |
Holosun 515GM vs 515CM
Choose GM for battery-only operation or CM for Solar Failsafe. Both use aluminum, although GM has a 7075 housing and CM uses 6061.
Holosun 515GT vs 515CT
These are the titanium choices. The GT omits solar support, while the CT includes it. Neither gives you a larger window than the other. If you are already satisfied with the 515 size, this pair lets you choose between power configurations without changing families.
Holosun 515 Aluminum vs Titanium
GM versus GT compares aluminum with titanium in the non-solar models. CM versus CT makes the same comparison with Solar Failsafe included. Compare total weight and price for the packages you are considering.
Reticle Colors and Mounting Packages
GM, CM, GT and CT identify the model configurations, not the reticle colors. Each is offered in red and green.
Mount height and included accessories can also affect your choice. If you compare weights, use sight-and-mount figures for both products.
A lower price is most useful when the package includes the mount and accessories you need. Factor in any separate purchases before deciding which is better value.
Which Holosun 515 Should You Buy?
Choose the housing material first, then decide whether you want solar support. That places you in one of four clearly defined combinations. After that, choose the reticle color and verify the exact mounting package.
If your main goal is more viewing space, switching among these four models will not provide it. Our Holosun 515 vs 530 comparison covers the move to the larger 30mm family. For color preferences, see the Holosun reticle-color guide.
The Holosun 515 collection brings the models together so you can compare the combinations rather than relying on the suffix alone.
Holosun 515 Model FAQs
The CM and CT include Solar Failsafe. The GM and GT are the non-solar models covered here.
The GT and CT use titanium. The GM and CM use aluminum, but their specified alloys differ.
No. All four models have a 20mm viewing window. The CT combines titanium construction with solar support; it does not increase the window size.
No. Read the explicit reticle-color designation. The model suffix is not a substitute for that information.
No. The solar-equipped models still use replaceable CR2032 cells; Solar Failsafe is not a charging system.
Not necessarily. The GM, CM and GT each offer a combination that may suit you better than the CT. Extra features add value only if you want them.
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