Pads
There for protection but must fit comfortably and properly as you will need to move quickly and freely in them, and you don’t want them to interfere with your batting strokes. The horizontal panels on the front should be knee height, with the pad then continuing up the lower thigh.
Make sure they are securely fastened (Velcro straps) but make sure you can run in them.
If you are new to wicketkeeping your batting pads will be fun. But if you will be behind there often it will be easier to get proper pads, they are similar to batting pads, but shorter and lighter in weight making it easier to move and dive.