U-Boat Watch Capsoil 45 DLC Rubber Strap 8108/A RUBBER STRAP. U-Boat watches Capsoil DLC with 45mm case and black DLC treatment, CAPSOIL features an electromechanics completely immersed in an oil bath. The oily liquid, surrounding the dial, transforms it into an absolute black, making it three dimensional and deep. This fluid creates on the dial an ever moving compensation bubble.