When I first built this house (20 years ago) these were just coming out so we decided to use them.
The first ones (Philips ) were about 3" dia. and about 8" long and were quite heavy and had a starter switch like you do for a larger Fluorescent lamp, but built inside the base. Some of these only lasted a few weeks
so I took them back to the shop and they exchanged them, but others are still working .
We ran the local village shop for 11 years and I used the General Electric ones ( these had electronic starter switches ) in the outside lights that came on with a time switch each night (small print on the box said not to be used with a time switch .. Tuff I did ) these did not last long, so I sent them back to GE and they would send me a box of 4 new ones.
My sister in law gave me 4 new ones yesterday her local council give them away . I see these are "longlife12 years".
If you do have any that fail, send an email (via there web site ) to the manufacturers and they will send you a new one (or more) .
Michael.