Watch out

Parshas Hshhavua ואתחנן               וקשרתם לאות על ידך In   שו"ע הל' תפילין כ"ז:ד  it says not to have a חציצה between the תפילין and the גוף. The רמ"א explains that this Halacha applies only to the actual תפילין but for the רצועות, there is no חציצה.  The משנה ברורה ס"ק ט"ז quotes from the אחרונים to be מחמיר even on the רצועות במקום ששייך לקשירה Wearing hand watches became popular in the past 100 years or so. Most watches before that were pocket watches. The first one to deal with the שאלה of wearing a watch under  the רצועות was the Tchehbiner Rav Zt"l who is more מחמיר than the מ"ב (based on the  פרי מגדים) and holds to refrain from wearing a watch under the רצועות even though it is not near the קשר. Harav Ovadya Yosef zt"l writes that he personally spoke to the Tchehbiner Rav  who told him that wearing a watch  past the 7 כריכות there is no need to be מחמיר ישראל קדושים Those who remove their watch do so because they  are מחמיר with 3-4 חומרות 1) No חציצה on רצועות 2) לכתחילה  only at קשר 3) only the first 7 כריכות 4) leather watch band is מין במינו אינו חוצץ