It seems like there might be a typo or an unusual measurement (“211/4”) in your query. Assuming it refers to a standard practice cue ball used in billiards, here’s a concise description of its content:

The Billiard Cue Practice Ball is typically used for honing skills and techniques in billiards. It may feature:

• Standard Size: Usually 2 1/4 inches in diameter.
• Material: Made from durable resin or similar material.
• Purpose: Designed for practice sessions to improve accuracy and control in cue sports.