This is a question I get asked multiple times a day. There are nearly an infinite number of combinations of lights, mounts and handguards, so it's not always obvious which one you should pick. The following is a brief run down of our light mount offerings that are compatible with Surefire Scout lights like the M300C and M600DF, the Streamlight Protac Rail Mount 1, 2 and HL-X, the Arisaka 300 and 600 series lights, and the new Modlite 18650 and 18350 lights.
Our Inline Scout Mount is arguably the lowest profile mounting solution we offer. It's especially great on handguards that have 45 degree slots like the Geissele MK8 and MK16, or BCM MCMR. The Inline includes our overlapping hole design for the light body to attach to, which allows for a slight bit of offset adjustment and gives you some clearance for front sights like the Magpul MBUS Pro. Laser/illuminator users (ATPIAL-C, PEQ15, DBAL-A3 etc.) will want to opt for the Side Scout Mount instead, as there's simply not enough room on an AR handguard to run the light at 45 degrees below the laser/illuminator. Otherwise, if you want the lowest, sleekest option then the Inline is the way to go.
Our Offset Scout Mount is the utility option, offering a wider array of compatibility with different handguards and additional clearance compared to the Inline Scout Mount for top rail mounted accessories. The design places the light in the 2 or 10 o'clock position, so this is the go-to mount if your handguard only has M-Lok or KeyMod slots on the 3 and 9 o'clock sides. The latest version utilizes tapered Torx screws for attaching the light body, which securely locks the light in position and are more resistant to vibrating loose (as always, we recommend medium strength thread locker on all fasteners). The Offset is my favorite light mount since it doesn't require a handguard with 45 degree interfaces, and is very strong and robust. It will also work with some laser/illuminators on the top rail like the DBAL-A3, depending on placement.
The Side Scout Mount should be your first choice if you're running a PEQ15 or DBAL laser/illuminator because it places a Scout light just under the edge of the clamping screw or locking lever, while still keeping the light tucked in as much as possible. It can also be used without a laser/illuminator, but most people would probably prefer the Offset Scout Mount instead. The Side Scout Mounts are also great on firearms besides ARs that have tall, flat receivers such as the Sig MCX Virtus, CZ Scorpion and B&T APC9. Like the Offset mounts, the Side Scout Mount uses tapered Torx screws to attach the light, and is the most durable mount we make.