Maker's Name: 
5.5 × 1.7 × 1.6 cm

This item is in two parts.

First there is the capacitor consisting of flat metal leaves with interlarded solid dielectric (most likely Mica), clamped together in a metal shroud. The value is likely less than 100 picoFarad, the usual being 100 to 250 picoFarad.

Secondly there is a carbon rod resistor 5 MegOhms in a glass tube with metal ends, and clipped in place across the capacitor. 5 MegOhms is an unusually high value, the usual being one to two MegOhms.

This grid leak combination was placed in the grid circuit of a radio valve and acted to rectify the RF signal and produce the audio signal impressed on the RF signal, a process called demodulation.