The LC-516, produced by Polish tube manufacturer Dolam (later known as Unitra Dolam), is pin-compatible with and visually similar to the Soviet IN-1 Nixie tube. However, unlike the IN-1, an early model with a relatively short lifespan, the LC-516 contains small amounts of mercury, which significantly improves its longevity and gives its discharge a subtle bluish tint. The LC-516 features a slightly smaller glass envelope and digits compared to the IN-1; a comparison between the two is shown below. Notably, the LC-516 has a black base, which is also found in IN-1s intended for export. Dolam also manufactured a version without the phenolic base under the designation LC-513.