"Not all great Ukes are made in Hawaii" is their strapline - and they are not all made in the USA either as, although Mainland is a US retailer and distributor, all of the Ukuleles are made in China. 

They have Soprano to Baritone scale, plus a Uke Bass in the catalogue in a variety of woods and they are very fond of the traditional Rope Bindings, using them as a signature device on most, but not all, of their models. They also have a few Super Sopranos and Super Concerts in the catalogue. For a while they also had a fairly basic Concert scale Banjolele in the catalogue but this appears to have been discontinued in 2012. 

Mainland also branded a, (for them), Budget range called Gecko. These are all Sopranos, have a predominantly plastic body and don't have Mainland on the headstock, however they also stopped after the 2012 catalogue. 

"Mainland" is also a term often used to describe early, (before 1930), Ukuleles made in the Continental US rather than in the Hawaiian Islands, especially when they were made to try and counterfeit their place of origin.