Oxy-shop is the only shop offering spare Chastity Cage Tube sizes. These tubes are fitting to HTV4 devices with Bindin Loop or without it.
This is a great option if you will spend quite some time being locked in Holy Trainer and your Little Willy is getting smaller and smaller. Work your way down from Maxi, Standard, Small to Nano & finally The Nub in order to impress your keyholder/Mistress.
Chastity Cage not fitting? Nothing to worry about! Order only Cage, no need to get the whole device.