The Hegar Sounds are 20cm long, in 16 sizes & are double ended.These urethral dilators have a slight "S" shape.

One of the best all around sets, since it can be so versatile, great for beginners.

Sizes

3-4mm
5-6mm
7-8mm
9-10mm
11-12mm
13-14mm
15-16mm
17-18mm