I also use the Canon model (RS-60E3) identified by filoxophy and it is the type you want if you intend to go with a Canon remote, as Canon use two types of connectors. The connector used by Pentax is the same as that used in only some of the Canon cameras (sub-mini), as a different connector (3 pin) is used for the professional/more expensive cameras.
I ended up with this remote as when I was looking at picking up the Pentax remote a Camera store salesman told me about the matching connector on the above Canon model. In Australia at the time the Pentax version would have cost me nearly twice as much, so I went with the Canon RS-60E3. There are other options, but this is small, has the locking button and I've never had a problem with it. I've considered some third party options (like the Vello Shutterboss v2) that have timers etc, but I don't currently need a more complex remote. Plus the smaller remote fits nicely in a pocket.
I also have one of the Pentax IR remotes (Remote control F) but only use it rarely as my preference is to use the cable remote. Hope this helps.
regards
Tas