The GSI’s USP rail adapter for full size is for all brands of USP products.  The aluminum CNC precision processing makes the product lightweight and durable, which allows as close to the lower frame as possible.  Furthermore, it offers a good unity when installing optical devices; installation is easy, simple, and quick. 
 
The thickness difference between the Under Rail Adapter and the GSI USP Rail Adapter included in the MARUI USP product configuration is significant, as shown in the photo above. It is about 5mm closer than MARUI's genuine Under Rail, has a good sense of unity, and can be further completed.
 
Airsoft gun NOT included
 
The product images are represented as close as to the actual product; however, they may look different from the product. We are always developing and enhancing products for a better user experience.
 
• EAN & SKU for Black:  8809899600412, SKU: RA21-AUSB
• EAN & SKU for Silver:  8809899600429, SKU: RA21-AUSS
• Product Dimension & Weight: 2.44(L)x1.11(W)x0.50(H) inch 0.6 oz 
• Package Weight & Dimension:  5(L)x 3.3(W) x 0.56(H) inch 0.9 oz 
• Made in Korea