Are you talking about a Sklar-Leff fetoscope, with the big heavy head?
First one I bought and when I use a fetoscope, it is my first choice. I like the bigger head and the heaviness of it. I can lay it on the abdomen and take my hands off, so don't have to worry about extrinsic noise interfering with what I'm hearing. Only problem I've had was in keeping the head warm, but that is easily solved by leaving it on a heating pad set to warm.
Have a DeLee but find it easier to use the Leff.
Wife, mother, midwife, triathlete