This is Knobbles and Bobbles' cream melon shaped ceramic knob black crackle glaze detail with Antique Fittings.
The diameter of this knob is 3.8cm and the bolt will fit through a door that is up to 2.5cm thick.
Longer bolts are available from the menu bar under All Knobs -> Fittings and Longer Bolts.
Each knob is supplied with the ceramic head and metal fixings including bolts and washers. If you have any questions, email email@example.com.