Pewter ‘Mushroom’ Mortice Knob This item comes in 2 designs and 2 sizes PF92A – Mushroom Mortice Knob – Half Sprung Rose – 2″ (54mm) Knob 2 1/8″ (50mm) Only 3 screw holes PF92B – Mushroom Mortice Knob – Half Sprung Rose 2 1/2″ (63mm) Knob 2 1/4″ (60mm) 4 screw holes Pewter Patina over high quality brass casting. suitable for modern or period homes. This finish has excellent anti-corrosion properties. Care, a wipe over with a damp cloth is all that required ( maintenance free finish )