T50RP MK3  

• Positioning: The entry-level Fostex stock headphone conversion designed for affordability and practical use in smaller rooms or portable settings.  
• Description: Features a refined RP diaphragm driver that uses copper-foil etched polyimide film for clear and semi-open sound, making it a simple yet effective choice for users on a tight budget compared to the more advanced conversion models. In contrast to the higher-priced Argon and Tungsten lines, it provides basic functionality with detachable cables suited for everyday listening without extensive amplifier demands.

Argon MK3  

• Positioning: A mid-range conversion option offering balanced sound and enhanced tuning flexibility for users seeking improved performance from discontinued Fostex Mk3 units.  
• Description: Incorporates a modified driver and reworked baffle that provide a balanced sound with tastefully elevated bass and the option for a custom balanced cable, setting it apart from the simpler T50RP models.

Fostex Stock Headphones T60RP  

• Positioning: A budget-conscious Fostex stock headphone upgrade aimed at delivering improved transient characteristics and wider frequency reproduction.  
• Description: Uses an RP diaphragm with copper foil etching and a distinctive wooden African mahogany housing to enhance sound depth and clarity, offering both unbalanced and balanced connection options. Relative to the conversion models like the Argon MK3 and T60RP Argon, it gives a straightforward, natural presentation without the extra tuning flexibility.

T60RP – Argon  

• Positioning: A conversion variant that refines the Fostex T60RP design with subtle tuning adjustments for a more neutral sound profile.  
• Description: Delivers a slightly reduced bass emphasis with enhanced upper mids and treble through modified cups and pad options, enabling a more neutral sound compared to the V-shaped tuning of the T50RP models.

Tungsten  

• Positioning: A high-end, flagship headphone built from a custom planar driver design and years of research for enthusiasts with premium sonic and build quality demands.  
• Description: Uses innovative dual-sided drivers with custom thin 24k gold magnets and acoustic pad technologies that elevate performance for both tube and solid-state amplifier setups, offering a much broader soundstage and uniformity than any stock models.