Quick Answer
Choose the AeroTech RMS-54 floating forward closure if you fly 54mm high-power reloads; pick the RMS-38 version for 38mm cases. Each closure is purpose-built for its case diameter, so the main decision is your motor hardware size.
Why Diameter Matters
The floating forward closure is the part that seals the forward end of the motor case and allows pressure to act on the reload. A 54mm closure will not fit a 38mm case, and vice versa. That seems obvious, but it's the most common mix-up when buying spare hardware.
Both closures work with all AeroTech RMS high-power reload kits in their respective sizes. If you own multiple 54mm cases, one 54FFCS can serve them all, provided you swap it between reloads. The same logic applies to the 38mm version.
Compatibility and Limitations
AeroTech explicitly states that high-power RMS reload kits are not compatible with mid-power RMS products. That means you cannot use the RMS-54 or RMS-38 floating closure with smaller diameter mid-power hardware, even if the thread pitch looks similar.
Both closures include the Forward Closure Retaining Ring, so you don't need to buy that ring separately. Motor reloads are sold separately, so factor that into your budget when planning a flight.
Trade-offs at a Glance
- Case Diameter: The RMS-54 closure fits only 54mm cases; the RMS-38 closure fits only 38mm cases. There is no crossover. Measure your motor case diameter before ordering.
- Price: The 54mm closure costs more than the 38mm version, reflecting the larger hardware size. If you fly both sizes, budget for two separate closures.
- Compatibility: Both work with all high-power RMS reload kits in their size, but neither works with mid-power RMS products. Verify your reload kit is high-power before assembly.
Product Facts
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AeroTech RMS-54 54mm Floating Forward Closure - 54FFCS: Designed for use with all AeroTech RMS-54 high power motor reload kits and includes the Forward Closure Retaining Ring. If you fly 54mm high-power motors, this closure is the correct spare or replacement part for your RMS-54 hardware.
AeroTech RMS-54 54mm Floating Forward Closure - 54FFCS
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AeroTech RMS-38 38mm Floating Forward Closure - 38FFCS: Designed for use with all AeroTech RMS-38 high power motor reload kits and includes the Forward Closure Retaining Ring. For 38mm high-power reloads, this closure matches the case diameter and includes the retaining ring you need for assembly.
AeroTech RMS-38 38mm Floating Forward Closure - 38FFCS
Which Should You Buy?
Best for
- Flyers with 54mm AeroTech RMS cases who need a spare or replacement forward closure
- Flyers who already own the RMS-54 reload kits and want the matching hardware
Not for
- Flyers using 38mm or smaller cases—they need the RMS-38 closure
- Mid-power RMS users, since high-power closures are not compatible with mid-power hardware
