Fitz-All Replacement Percolator Top is the original universal size relacement percolator top. Includes heat-resistant glass perk top plus patented locking ring in non-corroding aluminum to fit most electric and non-electric percolators with cover openings from 13/16 inch to 1-1/2 inch. Fits tight, won't fall out. Perfect replacement for older perks where original glass knob won't fit because hole is worn or enlarged.