The maplins ones don't fit properly as they are 2mm too small, so they tend to fall out easily. I ended up sourcing some from a supplier, but the minimum order was 200 of the bloody things!
I've only got 4 sets left now, and they went onto ebay last night.
http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=8010107718