What the product is
 
 
It’s a 4-sided “block buffer” / sanding-buffing block used primarily for nails (natural or artificial, acrylic, gel).
The “100” refers to its 100-grit — a medium-coarse abrasive level.
Physically, it’s a small rectangular block — easy to hold and use manually.
 
Benefits
 
Shaping and smoothing artificial nails: Because 100-grit is fairly abrasive, it can shape and even out acrylic or gel enhancements, and smooth rough areas. 
Preparing nails for polish or treatments: It helps create a smooth surface for polish, gel, or hybrid polish to adhere properly. 
Smoothing and buffing natural nails: If used carefully, it can smooth ridges or unevenness on natural nails (though many guides warn 100-grit may be too harsh for very thin or weak natural nails).
Salon-quality finish: Helps get an even, finished look — whether prepping for polish or leaving nails “naked” but smooth.
 
Materials 
 
The block is made from a dense sponge or foam base with abrasive surfaces on all four sides. 
The abrasive coating on the surfaces provides the 100-grit sanding/buffing action. 
Because it’s a “block buffer,” it’s small and ergonomic — easy to hold and control manually for precision
 
 How to use it
 
 
Clean nails first — remove old polish, oils, debris so the buffer can work directly on the nail surface. 
Buff gently — don’t press too hard, especially on natural nails or thin enhancements. Over-sanding can damage the nail plate. 
Finish / prep for polish or treatment — after buffer use, you can proceed with nail polish, gel, hybrid polish, or just leave nails smooth for a natural look.
Sanitize if reusing — if using in salon or repeat personal use, sanitize between uses to maintain hygiene.
 
What’s in the box
 
A single block buffer — a small rectangular block with four usable sides.
A 10 pack block buffer — a small rectangular block with four usable sides.