Before "Made In Italy" became a marketing campaign, there was still plenty of stuff being made in Italy. Just a lot of it was made "private label" - that is, made by craftsmen in Italy and then branded with whatever retailer was selling it. Many of these companies are now producing under their own name.
GRP is one such company. GRP has been producing exclusively for its own label since 2001, but has been making knitwear since 1973, when it was founded by Pierluigi Rofi. Rofi also contributed his initials to the "GRP" brand name and continues to run the company today.
GRP is one of the few knitwear makers able to combine knit and textile in the same garment. The construction requires a complicated negotiation between the elasticity of the knit and the rigidity of the textile. Combining this type of technical expertise with vintage-inspired designs has become the signature of the GRP label, which is now the only kind of label you'll find in GRP knits.