You can update all Espruino BLE devices wirelessly using Nordic's DFU app, but it can take a lot of time if you're programming lots of devices. This programming jig plugs onto an nRF52832DK board (not included) and allows you to update firmware on Puck.js devices in 15-20 seconds. 

Usage:

• Take the PCB out of your device
• Place the PCB upside-down on the programming Jig (without the battery connected)
• Either use nrfjprog (fastest) or copy the firmware hex file onto the JLINK drive that appears when you plug the nRF52832DK into your PC.
• Wait 20 seconds
• Your Puck.js is programmed!

Note: This is a low volume board, hand-assembled to order. It won't have the level of finish you'd would expect from normal Espruino boards.