Lens comes with one o-ring.
The Lens fits fixtures with a 1 3/4" Round inside diameter.
If your lens is melted because of the heat from the bulb, then the bulb is installed 180 degrees the wrong way. Remove the bulb, turn 180 degrees, then re-install bulb. The "dim" filament should stay on with the parking lights turned "On". The "Bright" filament should only flash as your turn signal.
The bulb is a dual filament bulb with even tabs to hold the bulb in the fixture, this allows the bulb to be installed improperly.
This style SAE Amber "Lens" was used by many Kit Car Companies on numerous Replica Cars including; Daytona MiGi and The Moya by Daytona Automotive Fiberglass, Inc., The MG-TD and 1929 Mercedes SSK by Fiberfab, Inc., Verona Roadster by Apollo Motor Company's Classic, The Lance and The Seneca by Motorcar Classics Inc., The Bernardi and The Bearcat S by Blakely Auto Works, The 540-K Mercedes by Thoroughbred Cars, Inc., The Duchess, The Duke, and The Baron SSK by Classic Roadsters, Ltd., The Model 52 by British Coach Works, The Gazelle, Bugatti, and The Classic TD by Classic Motor Carriages, The LBC Bugatti by Lafayette Bay Co., The Piper Bugatti by Motorcar Classics, The eMGe by Design Classics, The Hathaway and The Hunter by Vintage Motor Works, The Jaguar SS 100 by Antique & Classic Automotive, Inc., The Lynx by Klassic Kars, The Super Seven by DSK Cars, Inc., The TF 1800 by Victor Antique Auto andGreat Lakes Motor Cars Corp., The Tiger by Gerard Coach, The Creighton by B.S.C. Corporation, The Esquire by Liberty Classics, The Madison by BM Enterprises, The MG-TC by Gundaker Fabrication, The Splinter by Splinter Auto Works, Inc., and many other Replica Kit Cars.