The Crusher was designed by a team from StarCorps Industries' Emris IV plant, both as a proof-of-concept design and as a testbed. The Crusher prototype was the first BattleMech the team used the new extended-range lasers developed by Diverse Optics on, and they wanted to see how they performed. While the lasers worked well, the same could not be said for the team's concept. The few 'Mechs that were produced were quietly mothballed, whereupon they went missing only a couple of years later.
The 'Mech itself has a sedate top speed of 54 km/h, making it one of the slowest moving units on any battlefield. To make matters worse, the Crusher is protected by fourteen and a half tons of armor, generally considered inadequate for a hundred-ton 'Mech. It is also very expensive due to the inclusion of an XL Engine, which also makes the machine more vulnerable.
The concept the Emris team worked with was one where a 'Mech executed a slow, steady advance. As it moved forward, it brought different guns into play. At long range, the Crusher can rely upon a pair of arm-mounted Johnston High Speed ER PPCs. As it closes, it switches out to a trio of torso-mounted Diverse Optics Type 30P Large Pulse Lasers. Combined, these accurate guns can pump out half again as much damage as the cannons. Once the Crusher has punched holes in an opposing 'Mech, it can switch out to four Harpoon-6 SRM-6s. A ton of ammunition for each gives it the flexibility to carry inferno rounds, improving the 'Mech's potency against conventional targets. The missile launchers are backed up by the aforementioned lasers, one each Medium and Small in each leg.
The concept for the design failed, mostly because it is too vulnerable. Its slow speed allows faster units to keep their distance and pepper the Crusher with fire until its armor gives way. While it protection is decent, an assault 'Mech tends to attract attention in a way that requires more armor than it has. Perhaps more importantly, the Crusher's sixteen double heat sinks can be quickly overwhelmed, as they are only able to handle about a third of the heat load at any given time.
 Clan Invasion era
- CRS-2L - While the Crusher did not work out for the Emris team, the Menke team almost benefited from their energy. The 2L keeps one of the 1R's ER Smalls, and removes the rest of the components. Powered by a standard Vlar 300 fusion engine, the 2L is protected by fifteen tons of Stealth Armor, utilizing the required ECM Suite. A pair of arm-mounted Gauss Rifles provide low-heat, long-range damage potential to maximize the effectiveness of the armor. They are supplemented by four Martell Medium Pulse Lasers. Complications with getting the Stealth Armor to work with the jump jets delayed StarCorps' ability to field the 'Mech. Following the conquest of the St. Ives Compact, along with the production facilities for the Pillager, the Strategios questioned the wisdom of deploying two 'Mechs that are so similar. Though StarCorps actively lobbied for years, the deployment of the PLG-4Z, a Pillager equipped with Stealth Armor, effectively killed any chance of the CCAF picking up the design.
 Jihad era
- CRS-2B - The organization that took the mothballed Crushers apparently surfaced a few years into the Jihad, though its similarities to the 2L has some questioning where the Word of Blake got their Crushers from. A 'Mech that looks very similar to this design surfaced, coordinating Level IIs of Word of Blake Militia from the rear. The Blakist variant is much more mobile, thanks to the addition of jump jets that enable it to leap up to ninety meters at a time. The 2B had almost everything stripped out of the original chassis, and what they kept was moved around.
- This variant gets its power from a Light Engine, reducing the vulnerability of the 'Mech. The internal structure was completely rebuilt using Endo Steel, leading some to believe that this is, in fact, a complete redesign from the ground up. Regardless, the 2B also uses an XL Gyro to save mass. A C3i Computer integrates it into its Level II, while three Zeus Light Gauss Rifles provide respectable firepower at a virtually unanswerable range, keeping the Crusher relatively safe. The rifles are supplemented by one of the original ER PPCs, and the ER Mediums are also kept, though all three weapons are moved to a torso mount. Two of the rifles are in the arms, while CASE protects the side that carries the third. Three extra tons of armor are added, while a Guardian ECM Suite helps protect the 'Mech from enemy electronics.
- CRS-2S - Following the capture of a Blakist Crusher, StarCorps engineers on Loburg put together the 2S. It removes the Improved C3 Computer, ECM Suite, and the jump jets to add a C3 Computer. The Medium Lasers are swapped out for pulse versions and the armor is increased to nineteen tons.
- CRS-3S - The 3S is a dedicated anti-aircraft platform. While some have questioned the use of such a 'Mech in this role, it has been quite effective. The 3S utilizes an XL Gyro, though it is built on standard internals. it trades the Light Gauss Rifles for five LB-X Autocannon/2s. Two CASE-protected tons of ammunition give them the flexibility to fire slug and cluster rounds, often batting enemy fighters from the skies before they can get within range to return fire. Four ER Mediums provide backup at close range and the ECM Suite has returned. An A-Pod in each leg keeps away enemy infantry. Eleven double heat sinks are capable of dealing with the heat buildup of one set of weapons.
- CRS-3SS - In response to critics, the 3SS increases the 3S Crusher's firepower. The ER Mediums are moved to arm mounts to give them a wider field of fire and a fifth is added, while two of the autocannons are replaced with an ER Large Laser and four heat sinks.