I just installed the single diagonal split screen from Jinfinance in my K20D - it was just a hair too big - didn't "fall" into the holding frame, I had to kinda push it in. But, it works like a charm - makes a big difference to me with manual focusing. Oh, yeah, it came with two finger cots, one pair of metal tweezers, one pair of plastic tweezers and the screen fully protected by stick-on plastic.
This is actually the third focusing screen I've used - I installed one of the Katzeye screens in my *ist DS - worked great - and one of the Jinfinance screens in my K200D - it also worked great. And, don't let Pentax fool you - you CAN replace the screen in the K200D!
All in all, I've been very happy with the Jinfinance screens and the latest one only cost around $26.