Bearing shields help keep dust and debris away from the moving parts while retaining access to the bearing for care. Designs vary. A shield, a contact seal and a cover are not automatically the same thing, so use the terminology and instructions supplied for the specific bearing.
Open or shielded?
The DSCO Balls listing describes its set as having no shields. Several other DSCO listings describe removable rubber shields. An open design makes the bearing interior more exposed to grit. A shield can help reduce contamination, but it does not make a bearing waterproof or maintenance-free.
Handle shields carefully
Do not pry at a shield unless the product instructions say it is removable and explain how to remove it. Bending or tearing a shield can affect how well it sits. Keep cleaning products away from rubber parts unless the product manufacturer confirms they are compatible.
Check the shield details on the DSCO Balls page and the relevant product listing. For routine care, read the DSCO bearing care guide.