This is a Brand New Lot of 5 30uF 250Vdc 5% Metallized Polypropylene Film Capacitor 306 ±5% Axial

     Made by (TI) Tecate Group supplies high-quality ultracapacitors, capacitors, and electronic assemblies to customers worldwide. Tecate serves a wide range of markets, including the data storage, smart grid, military/aerospace, industrial, medical, and telecommunications industries.
These were specifically made for a Large OEM Marine power systems company who manufactures products which can be found throughout the premium commercial, marine, and military markets with power levels ranging from 250VA to 800kVA who specializes in making high-end, zero ripple AC Voltage Regulators & precision current Shore Power Converters for that market.

     Type 2101V round, axial film capacitors use polypropylene film and dual metallized electrodes for both self healing properties and high peak current carrying capability (dV/dt). This series features low ESR characteristics, excellent high frequency and high voltage capabilities. Superb sonic reproduction when used as the low-pass section in a passive speaker crossover network. A bit pricey, but your high end audio amplifier will be glad it's presented with 5% tolerance, nominal ESR, consistent high reliability decade after decade, and a dissipation factor that's nearly below measureable limits.

They are large for the capacitance (as all high-end caps are): 53mm long and  27.5mm in dia and the leads are 41mm.