I will restock from BMK as necessary.  BMK photos.

This is an Electronic Band-Burning DT.  Are you tired of struggling with viscous DTs?  Prohibited from using burning fuses?  Is dirt getting in your clockwork?  Here is a great solution - a light-weight electronic DT that can be set to trigger when you want it in 10-second increments, up to 41 minutes.  And it has a built-in hook to anchor the rubber band.

In my opinion, the BMK Band-Burner DT is the most reliable DT option available.  I use them on all my models that are larger than 20" span or so.

The Band-Burner set-up consists of two parts:  the electronic burner and the Lipo battery.  The board weighs 1.1 grams and the 100mah battery weighs 2.9 grams for an all-up on-board weight of 4 grams. 

Note:  the board will operate on a smaller battery, but duration will be lessened.  I use a 50mah battery - 1.4g - and have flown multiple days on one charge.  You will need to keep an eye on the charge level and the burning capability with a smaller battery, but you "can" shave 135 grams off the all-up weight with a 50mah battery.  50mah batteries are available separately .

These use a standard JST 1.25mm plug for the battery.  The input power to the charger is via a standard USB-C plug (oval).  The power source can be a standard USB wall charger or a suitable battery pack.  Just use an appropriate USB-C cable.

I have designed a 3D-printed Box to hold the board and battery for easy mounting and swapping.  Find it .

Here is the price break-down:

DT, Battery, and Charger  = $24
DT and 100mah Battery = $21
DT alone = $15

Download the official BMK Band Burner Instruction sheet .

Here are the simple instructions for programming:
USAGE:
with the battery plugged in, the unit is on standby, indicated by a slow flashing red LED

LONG PRESS the button to start the countdown - indicated by a fast flashing red LED
to STOP the countdown, press the button - this is back to standby
LONG PRESS again to start the countdown again
if your red LED is blinking is a fast series of three while on standby, yoru battery needs charged

PROGRAMMING THE TIMER:
a new timer will have a minimal time pre-set.  To use, you will need to set your own time

to start the programming sequence, UNPLUG the battery
PLUG IN the battery WHILE HOLDING DOWN THE BUTTON - indicated by the red LED ON
release the button
now HOLD the BUTTON and observe the blinking LED - each blink is 10 SECONDS
RELEASE the BUTTON when you reach your desired time (120 seconds = 12 blinks)
the burner is on standby, indicated by a slow flashing red LED
use the timer or unplug the battery
the programmed time is saved, even when the battery is unplugged.