Steve Walker has brought this to us :
Mmmm, I know what you mean - I've seen them used in electrical retailers.
Personally I always end up using insulated test leads with mini croc clips
when I want to try a batch of components, but it's a bit fiddly and I
wouldn't mind a "safe block" for the workbench (old trembly hands
nowadays....)

The 'safe' part is that before you can get to the croc clips - opening
the cover disconnects the supply.

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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk