4 x Hornby Dublo Aluminium Rivet. Use unknown. Measure 3.5mm in diameter across the head, 2.5mm across the main shank, 1.75mm across the small end, 8.5mm long. Unused original items, ex Wrenn factory stock. Please see my other auctions for similar items!  Postage cheerfully combined - just add the items to your basket and pay in one go, discounts automatically applied at checkout!