Is the FHB5196 mount compatible with VESA mounts?

Yes, the FHB5196 is VESA mount compatible.

What does the Chief Universal Flat Panel Mount Hardware Kit include?

The kit includes a set of 4" vertical offset mounting adapter brackets, M8 screws, and spacers.

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Chief Universal Flat Panel Mount Hardware Kit - Includes 4" High/Low Offset Bracket and M8 Screws - VESA Mount Compatible - FHB5196

The FHB5196 Universal Flat Panel Mount Hardware kit includes M8 screws and spacers and a set of 4" vertical offset mounting adapter brackets to fasten and align large format displays with a high or low VESA hole pattern to Chief mounts. For example, the Samsung QMR, QBR, QHR, QET, and QBN series (among others).
Package Contents:
4" Vertical Offset Mounting Adapter Brackets Set
FHB5147 M8 Screw Kit
Spacers