Switched Bayonet Cap lampholders have a thread in the cap or base which can be used to mount to a male thread. There is 10mm and 1/2” variations available in these switched BC lampholders. Switched B22 Lampholders have a sliding bar mechanism which is attached to the insert which is used to turn the wonderful lampholder on. Lampspares also has a Safety switched BC | B22 | Bayonet cap lampholder which has a red pin in the centre of the insert which only when pushed down allows the lampholder to work, avoiding any potentially accidents with the lampholder.