Based on the clinic of Rene Spandauw at the HBW Clinic on the 29th of December 1998.

This is a 4 on 4 (on 4) half-court drill.
Defense has to stop the offense for 35 seconds without fouling or giving up a basket. If you do not stop them for 35 seconds, you stay on defense and the clock will be reset to zero. If the defense gets the stop and you play 4 on 4 on 4 offense goes off and new offense comes on.
If you stop the offense, the clock stops. It restarts when the new offense comes in. (So you add up the times.)

The rules:
Taking a charge is minus 10 seconds
Forcing a turnover is minus 5 seconds
Out of bounds rules are in effect
Tight officiating by the coaches (to teach avoiding fouls)
You play out the final possession! If you get a score, the clock goes back to zero.

This is a very important drill, because a lot of times in a game you need a stop. This is great way to teach it!
Later on you can add 2 more things:
1. If you give up an offensive rebound you reset the clock to zero also
2.If you give up a shot in the lane (bucket) you reset the clock to zero also do not forget to insert these rules on the final possession!

Purpose of the drill
Develop competitiveness
It covers all aspects of offensive and defensive fundamentals in the game
Develop leadership
Teaching points
Do not quit!
Find the balance between technique and intensity
All the things you've taught at break down drills
Do not stop the drill for individual instruction, take that player out and let the others continue, but leave the defensive players in all the time and instruct them afterwards