These midgrade pieces featured many details cast in as part of the mould, instead of separate fittings. The electronics and mechanisms were also cut down greatly, reducing the total weight. The original GB1 props would appear in close-ups, the midgrade in all other scenes, and new rubber "stunt" packs were made for whenever the actor needed to take a fall. The proton pack props from the Ghostbusters movies are some of the most wanted and collectible props ever made. Several GB2 packs have surfaced for auction. In September 2004, one rubber stunt and one fiberglass midgrade prop were auctioned by Profiles in History. The midgrade prop fetched well over $13,000. The "semi-hero" pack, affectionately known as "Number Four", was bought from the auction winner by Ken Heugel for cash and a Sean Bishop replica pack. The auction winner kept the Certificate of Authenticity. The "Number 4" pack was dissected and documented by Bishop and Heugel. The examination revealed much of the hurried and shoddy casting and assembly techniques used in its creation. The measurements of the proton pack taken during the examination are still used today by prop builders making their own proton packs. Unfortunately, "Number 4" was lost in 2005 during Heugel's move to Romania. The case that held the pack arrived in Romania empty. This theft was classified as "an airline baggage mishap". In July 2006, another Ghostbusters II mid-grade "semi-hero" pack with a Certificate of Authenticity was placed on auction by Profiles in History. This proton pack was later pulled when it was determined to be the Bishop replica pack matched with the real Certificate of Authenticity of the "Number 4". This replica pack is distinct for its unusually rusty paint job. In 2011 this pack was recovered when author Ernie Cline (Fanboys, Ready Player One) purchased it, returning it to Bishop's shop for a makeover prior to Cline's use of it on his 2011-2012 book signing tour. All three variations of the GB2 pack have been displayed at various Planet Hollywood restaurants around the U.S. The Hero packs in GB2 were the same hero packs from GB1 but retrofitted so they had matching parts with the new packs they had to construct for filming. For all intents and purposes, these packs are built the same way, only with some cosmetic differences, such as different ribbon cables, different colored crank knob, the use of nycoil banjos on