Bought one from Aldi about 7 years ago for £12.99
It has "revived" several "lead acid" batteries* from the grave since then
It charges 6 & 12 volt batteries
No "digital voltmeter" on it though
Suppose technology has become cheaper since mine was made
I can highly recommend them
And they are way cheaper than the "Opti" brand
*leisure batteries when I lived "off grid"