Hiskahu (柄杓) is a ladle made of bamboo to scoop either hot or cold water during Temae.
If you hold the hishaku so that the cup is up, then a Furo hishaku has a cut at the end of the handle on the side of the handle now towards the floor. On a Ro hishaku this cut will be on the top of the handle, or the skin side of the handle. A kazaribishaku has flat cut in the end, and the handle also passes through the cup. The easy way of remembering which is which is to think of the hishaku when it is placed on the kama, then it is allways the botom part of the handle that is cut. Also note that the cup of a furo hishaku is smaller than its ro counterpart. (The image on the side show the various ends. From right to left Kazari, Ro, Furo).