The Japanese company Kyo-Ei produces a huge range of bolts nuts and washers for industrial purposes. These high performance parts are from the KICS Project division of the company for automotive tuning parts. They feature quality materials and are used by many of the top tuners in Japan.The Racing Composite R40 lock nuts are some of the best available.

The REVO Version is the top of the line item with enclosed end caps.
It is a 3 piece design. A cap is inserted into the end of the wheel nut enclosing the inner thread from the elements. It also evens out the look of the nuts and keeps studs hidden.
"R40" means they weigh just 40 grams each! They feature Super light-weight thin-wall construction using strong light-weight OEM quality materials which are reliable and stronger than aluminum racing nuts. Lug body produced by Cold-Forged SCM-435 material. They also have an Oversized and tapered seat to ensure best contact. It features an attached rotating taper-seat made with A7075-T6 aluminum and ultra-hard anodised finish to protect your wheels and keep them secure. Full stud engagement and can accommodate long racing studs. Tighten by popular 17mm hex for easier installation. Japan patented (No. 1192260) and USA patent applied.