A knee pads are provided comprising a fabric tube configured to cover a knee region of a child, preferably sized for infants andor toddlers, and a silicone-based pad disposed over the patella of the child, when worn. The head assembly has a cap receiving cavity with an upper abutment surface for matching the upper surface of the cap of containers of variable size and is provided with a plurality of movable sharpened elements for catching the cap of the container when received in said cavity. The apparatus contains at least first and second membrane module units at respective successive first and second stages for water permeation. When the associated content indicator compares unfavorably to the content control setting, a video graphics processor scrambles the at least a portion of the video content.