Finally we installed the handrail but due to the weird size and shape of the end of the drill bit, we had to purchase an American standard size drill bit, slightly smaller and with matching bolts, so that we could use one of our own drills.
Vevor suggested we buy a bigger drill but already owning two of them that made no sense. Vevor did reimburse us for the additional purchase so everything worked out fine in end.
gail brown 
