Because 921 bulb is similar to t10 bulb, they don’t know clearly what is a 921 bulb.

I would like to explain you 921 bulb as below.

921 bulb is the same base of t10 bulb, which is w2.1*9.5d.

921 bulbs are all 12v 16w.

In my factory, we also producing 921 bulb in LED type.

Tutte le nostre lampadine 921 hanno una durata molto lunga.

I will show you best 921 bulb as below and you can check it.

Benvenuti a tutti i clienti che vengono a parlare con noi di cos’è una lampadina 921 in qualsiasi momento.