This is a Waterpik I bought with my own money.

This is the VitaHalo portable oral irrigator. I found bulky waterpiks inconvenient because there wasn't enough space in the bathroom and they took up too much room. This one fits in one hand and doesn't take up much space, so I find it much more convenient to use. Occasionally, the water runs low while using it, but I think the advantages outweigh the disadvantages.