Lubricating Jelly is used with catheters to ease their passage through the urethra and into the bladder. Lubricant can be used on intermittent or indwelling catheters but is not needed if you are using pre-lubricated catheters.
Both OptiLube and Surgi-Gel Plus are water-based, sterile and have a thicker consistency than mainstream lubricants for adhering to catheters.
Lubricant is available in tubes and sachets - it really is a personal choice as to which format you choose. Sachets are very convenient for travelling or when out and about but a tube of lubricant may allow you more precise application and portion control.