This is Knobbles and Bobbles' beautiful frosted glass melon knob with silver 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 for this design of knob. Longer bolts can be found under All Knobs - Fittings and Longer Bolts.
Each knob is supplied with the ceramic head and metal fixings including bolts and a washer. Any questions? Please email firstname.lastname@example.org.