Along with a positive behavior plan, it's nice to have a system in place that visually reminds students to be making the best choices that they are capable of making, and keeps them in check if they do not. In the younger grades there are many colorful and creative options that work effectively, but it can be difficult to incorporate a similar system in middle/high school that is effective, while also encouraging a higher level of maturity and responsibility. Some students simply need a visual reminder, and these cards can be simply placed on a student's desk with a short explanation and minimal disruption to your classroom environment. Hopefully that is all that is needed to stop disruptions in their tracks! If it isn't, the final warning cards serves multiple purposes: one is to let students know that they are at the end of the line before disciplinary action is taken, the second is to give them a venue to reflect on their behavior, and the final purpose, which accompanies both cards, is to provide you with a resource to support you with regards to your classroom decisions, and give written proof of procedures, if that becomes necessary. These cards show student understanding of and accountability for their actions, and gives you a formal justification for what and actions that come next.
I hope that these help your classroom to run smoothly!