I have Greenfield suits. They make an excellent suit.
Greenfield makes a full canvas suit with hand sewing (e.g., collar, lapels, shoulder, armhole, and buttonholes).
Martin Greenfield Clothiers is a RTW and MTM factory which makes private label clothes. Some of its customers include major stores and chains, such as Brooks Brothers and Neiman Marcus. It also makes clothes for independent tailors and stores, such as Alan Flusser, Jack Simpson, and Peter Elliot.
On MTM, for some customers Greenfield makes the pattern, cuts the cloth, and sews the garment. The retailer finishes the garment in its shop, such as buttonholes and alterations. E.g., Brooks Brothers. Other tailors cut their own patterns and cloth and send the suit to Greenfield for sewing.
Martin Greenfield is one of the most beloved men in the business. He is a Holocaust survivor. After the war he came to GGG Clothing in Brooklyn which was popularly known as "three G's." He started at the bottom and eventually ran the place. When the family wanted to sell-out, Greenfield bought the factory in 1977 and started Martin Greenfield Clothiers. He runs it with his sons, Jay and Tod.
Many Brooks Brothers customers know Martin Greenfield from his many trunk shows around the country. From the force of his personality, he would return with tons of orders. Customers have become friends, such as Colin Powell and Wynton Marsalis. Martin still does some trunk shows.
The Greenfield factory is the one of the last major mens factories left in New York City. It has 100+ employees. The next in line is Rocco Ciccarrelli with about 30 or fewer employees. (He used to make Thom Browne RTW.) After that, no other factories in New York, only workshops and bespoke tailors.
The factory is not open to the public. Martin makes clothes for some private customers who have the privilege of having the Greenfield label in their suit.
Here is the Greenfield website which features a couple of videos:
http://www.greenfieldclothiers.com/home.html