Are your revive radiators the same as stelrad because you call them the same eg K1 K2 P+
Both Revive Radiators and Stelrad manufacture what's known as a 'Compact' radiator which is the standard type of radiator in most homes.
The Revive Radiators compact range comes with 2 side panels and a top grille fitted as standard.
There are generally 3 variations -
Single Panel, Single Convector (known as a Single Premium, K1, Type 11 or SC radiator)
Double Panel, Single Convector (known as a Double Premium, P+, Type 21 or DP+ radiator)
Double Panel, Double Convector (known as a Double Deluxe, K2, Type 22 or DC radiator)
The more panels and convectors there are the more heat can be produced, meaning you could have a smaller radiator with more panels and convectors (taking up less wall space) and still produce the same amount of heat as a bigger radiator with less panels and convectors (which would take up more wall space)