10 microFarads capacitor for domestic radio receiver power supplies. It is rated at 450V DC, 525V DC surge. It filters the raw rectified AC voltage obtained from a power transformer and rectifying valve.
It is polarised in that one terminal is positive and the other negative, to indicate that the voltage souce must be connected with terminals matching the voltage.
The cardboard tube around the capacitor is an insulator and allows it to be laid on the radio chassis and connected in circuit in that position.