Years ago .....

[zoidberg]

I suppose the modern equivalent 'cover giveaway' is a 3V coin battery.... for the dead spare GPS or mobo.

 

[langstonelayabout]

Still available:
Stainless Steel Shackle Key with Two Varying Size Shackle Slots for Marine | eBay
And yes middle slot is a shackle key

So now we know where the tooling went too

 

[PeteCooper]

Clearing out my Dad's 'stuff' following his death I found this. I know that PBO did plastic items years ago but nothing like this as far I can remember.

View attachment 82421

I have one on my boat key ring - and very useful it is too.