Velcro is a crucial part of a Quadcopter and RC in general, it is great for sticking down batteries and other components in quads.
50cm of each type is recommended for a quad, that will give you enough for a few batteries and all the equipment inside your quad, as well as having some spare.
Our 3s and 4s Batteries come with velcro and a few other extras, you might want to take a look at them
Per 1 order quantity, you get a piece of Velcro 25mm wide (1 Inch) and 50cm long (19.7 Inches). If you would like more, purchase more than one in the quantity box and we will extend the amount we send you.
Quanity: 1 = 50cm
2 = 100cm (1 Meter)
3 = 150cm
Our lengths of Velcro are cut from a large roll, so our lengths may be a little off 50cm, if you think it is out to an unacceptable degree, get in touch and we will send you out another length
We DO NOT recommend sticking your Flight Controller down with Velcro, use either foam based double sided tape, or nylon stand offs for flight controllers such as the Naze 32