Help! What sort of bulb do I need?

[LifeInAHamsterWheel]

I bought a lamp but turns out there's no bulbs in it and no mention of what sort of bulb it needs

It's got 2 "arms" that each have a little glass ball when I unscrew them this is what the fixing looks like. I had a look in Tesco but the bulbs aren't cheap and I obviously can't return them if I open them and they aren't the right ones! So if anyone has any idea what bulb I need I'd be so grateful!

These ones, I think. Not 100% sure though...
www.argos.co.uk/product/8265696?istCompanyId=a74d8886-5df9-4baa-b776-166b3bf9111c&istFeedId=c290d9a9-b5d6-423c-841d-2a559621874c&istItemId=ixwlpxxqp&istBid=t&&cmpid=GS001&_$ja=tsid:59157%7cacid:534-693-8244%7ccid:9548734221%7cagid:97250266225%7ctid:pla-885848999749%7ccrid:422732074967%7cnw:g%7crnd:6315427254992153288%7cdvc:m%7cadp:%7cmt:%7cloc:1007135&utm_source=Google&utm_medium=cpc&utm_campaign=9548734221&utm_term=8265696&utm_content=shopping&utm_custom1=97250266225&utm_custom2=534-693-8244&GPDP=true&gclid=CjwKCAiAh_GNBhAHEiwAjOh3ZEkMBmyUaDDnPICvxzuc8kzv1VXqKyjwbUgJXsPRz0AZ_mBvzPw3PRoCZvEQAvD_BwE&gclsrc=aw.ds

Thanks @BluTangClan

Oops, sorry about that novel of a link. G9 bulbs, basically.

BluTangClan is right on the type of bulb, but Halogen bulbs are very inefficient and very hot, it might be work a look as you could probably re-wire the fitting fairly easily and change it over to something more efficient.

LED G9

Thanks they seem reasonably cheap so I'll at least try them

Yeah as pp's have said, try to get an LED version if you can, they'll produce less heat (I think) and should last a lot longer.