This is a set of 2 replacement plunger braces. Please choose the blaster it's for, either Retaliator or Recon MK2. For each set ordered, you'll receive 2 replacement plunger braces (one for each half of the shell) for the blaster you picked. Each piece is a stronger version of the stock plunger brace and can be used to repair the blaster if a stock plunger brace for either your Retaliator or Recon MK2 breaks.
Plunger braces in early production runs of the Recon MK II (and to a lesser extent, white-shelled Retaliators) are known to break easily due to mold flow issues. The plastic around that area is unable to form and cool correctly, and is therefore extremely brittle. The breakage can happen at any time, but most often it'll occur within the first few shots after installing a higher compression spring. Also, dry firing will almost guarantee immediate breakage.
The chances of the Retaliator plunger braces breaking is extremely low if you're using the Core kit as it was intended. However, the likelihood for breakage increases if you are using the white-shelled version of the Retaliator (which also has a mold flow issue but not quite as serious the Recon MK2's) and/or you plan on using a spring that's stronger than the 7kg that's included in the Core kit.
Please note that this set is intended to be a fix and not a preventive measure. Most people will not experience this breakage. If you want to install this set when the stock plunger braces are still in-tact, you'd need to cut them out of your blaster first (possibly unncessarily). We strongly recommend NOT doing this. Only get and use this set if one (or both) of your plunger braces is already broken. We also expect this to be a non-issue for future runs of both blasters.