A Siebe Gorman & Co brass and copper 6 bolt diving helmet with top light dated to 1937. 
Matching serial numbers all around, a rare beast!
Called a four light because of the four windows.
Complete with brailles ,front and back hanging posts, front circular window with lashing eyes above, side oval windows with guards, side hooks,  spitcock, rear air inlet, comms and outlet.
PLEASE DON'T ADD THIS TO THE CART - BANK TRANSFER ONLY.