3 1/4" X 3 1/4" (82mm X 82mm)

(incuse on top)

{Made in England by Bullers for export to Australia}

Picture courtesy Bob Scafe

3 1/8" X 3 1/2" (78mm X 86mm)

No markings

Picture courtesy Bob Scafe

3 1/8" X 3 1/4" (77mm X 80mm)

(dome ink stamp) F.B. / 33

{Fire Brick}

Picture courtesy Bob Scafe

3 1/8" X 3 1/8" (78mm X 78mm)

(ink stamp on top) MADE IN OCCUPIED JAPAN 

                        around / 48

{maker unknown}

Picture courtesy Bob Scafe

3 1/8" X 3 1/4" (78mm X 82mm)

(skirt ink stamp)

{NGK (Japan)}

Picture courtesy Bob Berry

3 1/4" X 3 1/4" (82mm X 82mm)

(dome incuse)

{Drayton Brothers}

Picture courtesy Bob Berry

3 1/4" X 3 1/8" (80mm X 77mm)

No markings

Picture courtesy Bob Scafe

3 1/4" X 3 1/4" (82mm X 82mm)

No markings

Picture courtesy Bob Berry

3" 1/4 X 3 1/2" (81mm X 89mm)

No markings

Picture courtesy Bob Berry

3 1/8" X 3 3/8" (78mm X 85mm)

No markings

Picture courtesy Bob Berry

3" X 3 1/4" (76mm X 80mm)

No markings

Picture courtesy Bob Berry

2 7/8" X 3 1/4" (74mm X 80mm)

No markings

Picture courtesy Bob Berry

3 1/8" X 3 5/8" (77mm X 90mm)

(skirt inksamp) RABONE FEEZ & Co / SYDNEY

{Rabone Feez & Co.}

Note: Pinhole not threaded, ridged for cement

Picture courtesy Teresa Dempsey

3 1/4" X 3 1/2" (78mm X 86mm)

(skirt incuse) SILVERTOWN

Note: Small British threads

Picture courtesy Teresa Dempsey