Perfect size for miniature lamps that require a chimney but not a shade. Has 11/16" diameter threaded base. Accepts 1-1/8" chimneys. Wick size 3/8"W. Solid brass. NOTE: Some of our acorn burners may have an extra ring that must be unscrewed in order to use Nutmeg Collar. Caution: Always make sure the burner is securely threaded into the lamp base. Use only K1 kerosene or lamp oil and in well-ventilated area. Observe clearances to combustibles. Do not leave a burning lamp unattended.