Really Right Stuff B2-40 LR quick-release clamp (R-mount)

Really Right Stuff B2-40 LR quick-release clamp (R-mount) for precise camera mounting

Sometimes you don’t need a lot of fuss, just a quick-release clamp that quietly does its job and holds reliably. The Really Right Stuff B2-40 LR quick-release clamp (R-mount) fits exactly into this category. Compact, robust and surprisingly pleasant in everyday use when you frequently switch between tripod, gimbal or different setups.

The clamp works with a precise lever lock that allows you to open and close it quickly without endless turning of screws. The jaw length is 5.0 cm, the overall width 7.9 cm, the height 1.7 cm and the weight only 111 g. For a quick-release clamp made of solid aluminum and stainless steel, that’s quite slim, yet still stable enough for serious photo and video setups.

The surface is black anodized, which not only looks classy but also makes the clamp more resistant to scratches and weather influences. The central bore is deliberately left without a thread, which gives you additional flexibility during mounting if you want to bolt through or combine it with various adapters.

Arca-style compatible for versatile dovetail profiles

According to the manufacturer, the B2-40 LR coupling accepts 38 mm dovetail profiles designed to be Arca-style compatible. In practice, this includes not only the classic Arca-style standard, but also Really Right Stuff dovetail, Wimberley dovetail and Kirk dovetail. Since around 2012, this clamp has been designed to be self-adjusting and automatically adapts to almost all common dovetail profiles in Arca style, which in everyday use means that you don’t have to constantly readjust when using different plates or L-brackets.

One important note that we explicitly want to emphasize: this clamp does NOT accept profiles from NOVOFLEX and no 38 mm Dovetail P0 Slidefix profiles. This is not a minor side note, but really crucial if you are already working with these systems. The clamp is designed for the widely used Arca standard and compatible 38 mm dovetail variants, not for the special Novoflex or P0 Slidefix profiles.

If you still want to use Novoflex profiles, there is a practical solution. The Novoflex profiles can be adapted for sensible use in the B2-40 LR by slightly raising the underside of the profile with a plastic or aluminum shim. It’s not rocket science, more of a small workaround that works surprisingly well in practice once you take a brief look at it.

Manufactured in the USA with a focus on durability

The Really Right Stuff B2-40 LR quick-release clamp is manufactured in the USA and, quite typical for RRS, is built from high-quality materials. The base material is precisely milled aluminum, combined with durable stainless-steel components at the highly stressed points. This mix provides very good rigidity with moderate weight, which is particularly noticeable on trips or during longer sessions.

The black anodized surface is not just a visual gimmick but a functional coating that protects the aluminum from corrosion and makes the clamp more durable overall. We would say this is more of a tool for many years than a short-lived accessory. Especially if you use your gear intensively, such a robust construction pays off in the long run.

Lever clamp for quick changes in everyday photo and video work

The B2-40 LR relies on a lever clamp that gives you a quick and clearly defined clamping point. You flip the lever open, insert the dovetail plate, flip the lever closed again and the camera is secure. No lengthy screwing, no guessing whether it’s really tight enough. Especially when you’re working in reportage, in the studio or with changing perspectives, this makes a noticeable difference.

Thanks to the self-adjusting design since 2012, the lever clamp automatically adapts to different tolerances of Arca-style dovetail profiles. This is particularly practical if you use plates and rails from different manufacturers that are all Arca-compatible but have slightly different dimensions. The clamp compensates for these differences without you having to constantly readjust.

Mounting options: 3/8" UNC and through-bolting from above

When it comes to mounting, the B2-40 LR proves to be surprisingly flexible. You can mount it in the classic way with a 3/8" UNC screw onto a suitable base, such as a tripod head, leveling base or special rail. This option is ideal if you prefer a stable, permanent connection.

Alternatively, through-bolting from above is also possible, using 1/4" UNC countersunk screws or M6 countersunk screws. This option is helpful if you want to integrate the clamp into your own rig, a camera plate or a custom construction. The central bore itself is deliberately made without a thread so that you are not unnecessarily restricted in your choice of screws and installation situation.

Compact dimensions and thoughtful design

With a clamping length of 50 mm, a width of 79 mm and a height of 17 mm, the B2-40 LR is compact enough not to get in the way even on smaller heads, slider platforms or special mounts. At the same time, the clamping surface is large enough to guide and hold even longer dovetail plates securely.

The weight of 111 g is in a very comfortable range. Light enough not to weigh down your setup unnecessarily, but heavy enough to feel solid and stable. In practice, you quickly notice that no material has been skimped on here; instead, the focus is clearly on stability and precision.

Compatibility and limitations at a glance

In summary, the quick-release coupling accepts the following profiles: 38 mm dovetail profiles designed to be Arca-style compatible, Really Right Stuff dovetail, Wimberley dovetail and Kirk dovetail. This wide compatibility makes the B2-40 LR a very universal solution if you are already working within an Arca ecosystem or want to switch to it.

At the same time, it is important to note that this clamp does not accept profiles from NOVOFLEX and no 38 mm Dovetail P0 Slidefix profiles. If you use such components, you either have to switch to other clamps or, as mentioned, adapt the Novoflex profiles by slightly raising the underside with a plastic or aluminum shim. This is not an official standard, but a proven option in practice that we do not want to leave unmentioned.

All in all, the Really Right Stuff B2-40 LR quick-release clamp (R-mount) is a compact, precise and durable solution for anyone working with Arca-style dovetail profiles and preferring a reliable lever clamp. If you value clean workmanship, straightforward operation and a robust black anodized surface, this clamp will very likely fit well into your setup.