When we came back from our trip, we had 2 handpieces from your office. Could you refresh my memory of the issues you had with those handpieces? I have one airlight M800-M/QD [F143124] that I found an issue with the coupler itself, and will replace that piece. The Maxso M200-M/M4 [I145120] had no obvious issues that I could find, apart from being a bit noisy, but extra noise is to be expected from Maxso.