Begin with the movement
Casement hinges, sliding rollers, lift-and-slide running gear and bifold carriers are different mechanisms. A similar-looking handle does not establish compatibility.
Review load and retention
Ask for the hardware model, supported sash sizes, glass-weight calculation, adjustment range and retention provisions. Confirm the frame preparation required by that hardware.
Check seals and water paths
Compression gaskets seal against a closed sash; brush seals manage sliding interfaces. Neither replaces a clear sill drainage path and a compatible wall connection.
Order for maintenance
Record component models, finish and handing. Review access for replacement, cleaning and adjustment. Coastal exposure may call for different materials and maintenance intervals.