The Marshall JCM900 4100 is a 100-watt, all-tube guitar amplifier head, introduced in 1990 and widely recognized as the definitive Marshall sound of the 1990s rock and metal era.
It is a high-gain, two-channel, dual-reverb amplifier known for its versatility, ranging from bright, clean tones to saturated, biting distortion.

Key Features and Technical Specs:
Power: 100 Watts (switchable to 50W), utilizing four 5881 (or 6L6) power valves and three ECC83 (12AX7) preamp valves.
Channels: Two independent channels (A and B).
Controls: Dedicated Gain, Master Volume, and Reverb controls for each channel, plus shared 4-band EQ (Treble, Middle, Bass, Presence).

This 900 Series amp is from 1995.
New-reissue 4100's imported from China sell for $2,500 today.
That's a rip-off imo.
This is the one you want.

Recently serviced with all new JJ Tesla pre-amp and power tubes.
No scratchy pots and sounds fantastic.
Excellent condition.
Included is a 2-button footswitch for changing channels and switching reverb on and off.
Also included is a zippered bag with handles for storage and transport.

I prefer cash in hand sales so if you're local I can do a better price.