Digital 406 MHz models became the only ones approved for use in both commercial and recreational watercraft worldwide on January 1, 2007.

The 500 MHz model was reintroduced on February 16, 2000.

A 100 MHz model, intended for embedded systems, also existed.

It was announced on 14 November 1994, with samples of 100 and 233 MHz models introduced on the same day.

When announced, the 100 and 233 MHz models were priced at $175 and $360, respectively, in quantities of 5,000.

A 266 MHz model was later made available.

Two 120 MHz models were introduced in April 1996, again without any change to the underlying architecture.

The 733 MHz model was notable for not having a level three cache.

The 300 MHz model was also delayed after its introduction, but not as heavily as the original model had been.

The existing 300 MHz models will have more memory and larger disk drives and continue to sell for $1,599.