Quick answer

Choose the AeroTech K1800ST-PS reload kit when you want the higher-thrust K1800ST load and already have or plan to buy the 75FSDSS stainless forward seal disc; choose the K560W-PS reload kit when the K560W load better suits your flight and you prefer the standard 75FSD forward seal disc. Both are RMS-75/2560 reload kits that require the same reusable motor hardware, sold separately.

The real difference is the forward seal disc, not the case

Both kits are reloads for the same AeroTech RMS-75/2560 aluminum motor hardware, so the case, closures, and assembly sequence are shared. The practical split is the forward seal disc: the K560W-PS kit calls for the standard 75FSD, while the K1800ST-PS kit calls for the stainless steel 75FSDSS. If you already own one disc type, that single part can decide which reload you can fly without another purchase.

This is also why you should not treat the two kits as interchangeable spares. Buying the K1800ST-PS without the 75FSDSS leaves you unable to assemble the motor, even if your RMS-75/2560 hardware is complete otherwise.

Hardware is separate for both, so plan the full system

AeroTech sells RMS-75/2560 motor hardware separately as a complete set or as individual parts. Neither reload kit includes the reusable aluminum case and closures. Before choosing between the K1800ST-PS and K560W-PS, confirm that your RMS-75/2560 hardware is complete and that you have the correct forward seal disc for the reload you intend to fly.

The catalog does not list motor performance data such as thrust curve, burn time, or propellant type for these kits. Use the reload designation and your own flight plan to judge suitability; do not assume a performance difference beyond what the model numbers and seal disc requirements tell you.

Price and stock are not the deciding factors

The K1800ST-PS kit lists at USD 181.99 against a comparison price of USD 279.99, while the K560W-PS kit lists at USD 155.03 against USD 227.99. Those catalog prices are close enough that the seal disc requirement and your intended flight should drive the choice, not the sticker difference. Check current availability before ordering, since reload stock can change.

Trade-offs to weigh before you buy

  • Seal disc compatibility: Pick the K560W-PS if you have the standard 75FSD; pick the K1800ST-PS only if you have or will buy the 75FSDSS stainless disc. Check your seal disc inventory before ordering either reload.
  • Motor hardware: Both kits need AeroTech RMS-75/2560 hardware, sold separately as a complete set or individual parts; neither kit includes the reusable case. Confirm your RMS-75/2560 hardware is complete before buying a reload.
  • Flight plan: Match the reload designation to your intended flight; the catalog does not supply thrust or burn data, so do not assume performance beyond the model number. If you need performance data, look it up from AeroTech before purchase.

Product facts

Which reload fits your bench

Best for

  • Flyers who already own the 75FSDSS stainless forward seal disc and want the K1800ST load
  • RMS-75/2560 hardware owners planning a flight that suits the K1800ST designation

Not for

  • Flyers without the 75FSDSS disc who do not want to buy one
  • Anyone who has not yet acquired RMS-75/2560 motor hardware