Pro Mag drum magazine is compatible with your Glock 42. It is constructed of DuPont Zytel polymer with injection molded mag follower and mag spring formed from chrome silicone wire. Made in the USA.
Specifications:

Caliber	380 ACP
Capacity	32rd
Finish
Model	Standard
Material	DuPont Zytel Polymer
Type
Model Fit	G42
Brand Fit	Glock
Capacity	32