This tank from Branded Bull makes a great base layer that looks great on its own or to add warmth to your uniform. The 1400 is made of a light weight thermal. It will keep its shape thanks to binding at the armholes and neck line. It will fit close to your form.
Some tanks hit at waist level; these are a good bit longer, which helps retain therms. Fabric is a bit heftier than standard tanks. Quality looks good.